Pouch-type battery case and secondary battery including same

Abstract

A pouch-type battery case according to an embodiment of the present invention may include a barrier layer having a metal material, an inner polymer layer located inside the barrier layer and having a first polymer material, an outer polymer layer located outside the barrier layer and having a second polymer material, a fire-extinguishing coating layer located on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent, and a protective layer located inside the fire-extinguishing coating layer.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0134413 filed on October 8, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery case and a secondary battery including the same. [Background technology]

[0003] In general, secondary batteries refer to batteries that can be charged and discharged, unlike primary batteries that cannot be recharged, and are widely used in electronic devices such as mobile phones, laptops, and camcorders, as well as electric vehicles, etc. In particular, lithium secondary batteries have a larger capacity than nickel-cadmium batteries or nickel-metal hydride batteries, and their use is rapidly expanding due to their high energy density per unit weight.

[0004] The secondary battery includes an electrode assembly and a battery case that houses the electrode assembly. The electrode assembly includes a positive electrode and a negative electrode that are alternately stacked with a separator interposed therebetween. Specifically, the positive electrode is fabricated by applying a positive electrode active material slurry to a positive electrode current collector, and the negative electrode is fabricated by applying a negative electrode active material slurry to a negative electrode current collector.

[0005] Meanwhile, when a secondary battery malfunctions due to exposure to high temperatures, internal short circuits, external short circuits, overcharging, or over-discharging, the heat generated by the decomposition of the organic electrolyte can cause the separator to shrink, leading to direct contact between the positive and negative electrodes and increasing the likelihood of a short circuit. Such a short circuit can cause a rapid transfer of electrons within the battery, potentially resulting in an explosion and fire, posing a safety risk. In particular, when an electrical malfunction such as overcharging, over-discharging, or an external short circuit occurs, a large current flows, generating heat at a higher temperature in the current collector than in the active material layer due to the low thermal conductivity of the current collector. Therefore, when this heat diffuses, the positive electrode active material containing a metal oxide decomposes and recrystallizes, generating flammable gases containing oxygen, which can lead to a larger explosion.

[0006] In particular, because secondary batteries are generally used with multiple battery cells aggregated into modules or packs, if a fire breaks out in any one battery cell, it could lead to a large-scale fire. Therefore, there is a need for the development of technology to extinguish secondary battery fires. Summary of the Invention [Problem to be solved by the invention]

[0007] One of the problems to be solved by the present invention is to provide a pouch-type battery case that can prevent the spread of fire using a fire extinguishing capsule, and a secondary battery that includes the same.

[0008] Another object of the present invention is to provide a pouch-type battery case and a secondary battery including the same that can prevent the fire-extinguishing capsule from bursting due to a simple rise in internal temperature. [Means for solving the problem]

[0009] A pouch-type battery case according to an embodiment of the present invention may include a barrier layer having a metal material, an inner polymer layer located inside the barrier layer and having a first polymer material, an outer polymer layer located outside the barrier layer and having a second polymer material, a fire-extinguishing coating layer located on one side (one surface) of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent, and a protective layer located inside the fire-extinguishing coating layer.

[0010] The fire-fighting coating layer may be located outside the barrier layer, and the protective layer may be located between the fire-fighting coating layer and the barrier layer.

[0011] The fire-fighting coating layer may be located inside the barrier layer, and a protective layer may be located between the fire-fighting coating layer and the inner polymer layer.

[0012] The capsules of the fire-fighting coating layer may rupture at a first temperature and the protective layer may melt at a second temperature higher than the first temperature.

[0013] The capsules of the fire-extinguishing coating layer may rupture at 120 to 130 degrees Celsius, and the protective layer may melt at 150 to 250 degrees Celsius.

[0014] The thickness of the protective layer may be less than the thickness of the fire-fighting coating layer.

[0015] The thickness of the protective layer may be 1 / 100 or less of the thickness of the fire-fighting coating layer.

[0016] The capsules of the fire-fighting coating layer may have a diameter of 50 μm to 300 μm.

[0017] The fire-extinguishing agent encapsulated in the fire-extinguishing coating layer may include fluoroketone.

[0018] A secondary battery according to an embodiment of the present invention may include an electrode assembly and a pouch-type battery case that the electrode assembly is housed in. At least a portion of the pouch-type battery case may include a barrier layer having a metal material, an inner polymer layer positioned inside the barrier layer and having a first polymer material, an outer polymer layer positioned outside the barrier layer and having a second polymer material, a fire-extinguishing coating layer positioned on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent, and a protective layer positioned inside the fire-extinguishing coating layer.

[0019] The seal portion of the pouch-type battery case may not include the fire-extinguishing coating layer and the protective layer. [Effects of the Invention]

[0020] According to a preferred embodiment of the present invention, the capsules provided in the fire-extinguishing coating layer are filled with a fire-extinguishing agent, and the capsules rupture when the fire-extinguishing coating layer reaches a specific temperature, thereby preventing the spread or transfer of a fire that has occurred inside or outside the secondary battery.

[0021] In addition, the protective layer is provided inside the fire-extinguishing coating layer, and can delay the temperature rise of the fire-extinguishing coating layer due to heat generated by the electrode assembly, thereby preventing the capsules of the fire-extinguishing coating layer from bursting due to heat generated during normal operation, such as charging and discharging of the electrode assembly.

[0022] In addition, the present invention includes effects that can be easily predicted by a person skilled in the art from the configuration of the preferred embodiment of the present invention.

[0023] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in these drawings. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is an assembly diagram of a secondary battery according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view of a pouch-type battery case according to an embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of a pouch-type battery case according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention can be embodied in various different forms and is not limited to the following embodiments.

[0026] 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 will be omitted, and when adding reference symbols to components in each drawing in this specification, the same or similar reference symbols will be used throughout the specification to refer to the same or similar components.

[0027] Furthermore, the terms and words used in the specification and claims of this application 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 invention, based on the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0028] FIG. 1 is an assembly diagram of a secondary battery according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the secondary battery according to an embodiment of the present invention.

[0029] As shown in FIG. 1, a secondary battery 1 according to an embodiment of the present invention may include an electrode assembly 10 formed by stacking a positive electrode, a separator, and a negative electrode, and a pouch-type battery case 20 (hereinafter referred to as a "battery case") that houses the electrode assembly 10.

[0030] The electrode assembly 10 may be a laminated structure including two electrodes, a positive electrode and a negative electrode, and a separator interposed between the electrodes or disposed on the left or right side of one of the electrodes to insulate the electrodes from each other. The laminated structure may be formed in various forms, including but not limited to a structure in which positive and negative electrodes of a predetermined size are stacked with a separator interposed therebetween or wound into a jelly roll shape. The two electrodes, i.e., the positive electrode and the negative electrode, may be formed by applying an active material slurry to a metal foil or metal mesh electrode current collector. The positive electrode current collector may include an aluminum material, and the negative electrode current collector may include a copper material. The active material slurry may be formed by stirring a granular active material, an auxiliary conductor, a binder, a plasticizer, and the like in a solvent, and the solvent may be removed in a subsequent process.

[0031] The electrode assembly 10 may be provided with a plurality of electrode tabs 11, which may protrude to the outside of the electrode assembly 10 and act as a path for electrons to move between the inside and outside of the electrode assembly 10.

[0032] More specifically, the electrode current collector of each electrode included in the electrode assembly 10 may include a portion coated with an electrode active material and an end portion where the electrode active material is not coated, i.e., a non-coated portion. The electrode tab 11 may be formed by cutting the non-coated portion, or may be formed by connecting another conductive member to the non-coated portion by ultrasonic welding or the like.

[0033] The plurality of electrode tabs 11 may include a positive electrode tab 111 connected to a positive electrode and a negative electrode tab 112 connected to a negative electrode. The positive electrode tab 111 and the negative electrode tab 112 may protrude in the same direction from one side of the electrode assembly 10, but are not limited thereto, and may protrude in different directions.

[0034] The lead 12 may be connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. A portion of the lead 12 may be surrounded by an insulating portion 14. The insulating portion 14 may be located only at the seal portion 24 where the upper case 21 and the lower case 22 of the battery case 20 are heat-sealed, and may be adhered to the battery case 20. Alternatively, the insulating portion 14 may prevent electricity generated from the electrode assembly 10 from flowing to the battery case 20 via the lead 12, thereby maintaining the seal of the battery case 20. Therefore, the insulating portion 14 may be made of a non-conductive material that is difficult to conduct electricity. Generally, the insulating portion 14 is made of a relatively thin insulating tape that is easy to attach to the lead 12. However, the insulating portion 14 is not limited to this, and various materials may be used as long as they can insulate the lead 12.

[0035] The lead 12 may include a positive electrode lead 121 having one end connected to the positive electrode tab 111 and extending in the direction in which the positive electrode tab 111 protrudes, and a negative electrode lead 122 having one end connected to the negative electrode tab 112 and extending in the direction in which the negative electrode tab 112 protrudes. In addition, the ends of the positive electrode lead 121 and the negative electrode lead 122 may protrude outside the battery case 20 to supply electricity generated inside the electrode assembly 10 to the outside. That is, the end of the lead 12 protruding outside the battery case 20 may be electrically connected to an external terminal.

[0036] The positive electrode lead 121 and the negative electrode lead 122 may be made of different materials. More specifically, the positive electrode lead 121 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 122 may be made of the same copper (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni).

[0037] Meanwhile, the battery case 20 may be a pouch made of a flexible material, and may be sealed after accommodating the electrode assembly 10 such that the ends of the leads 12 are exposed. The battery case 20 may include an upper case 21 and a lower case 22. The lower case 22 may have a cup portion 23 formed therein and a receiving space 231 for receiving the electrode assembly 10, and the upper case 21 may cover the receiving space 231 from above to prevent the electrode assembly 10 from falling out of the battery case 20. Here, the upper case 21 may also have a cup portion 23 with the receiving space 231 formed therein, and the electrode assembly 10 may be received from above. However, this is not limited thereto, and various other configurations are possible, such as the cup portion 23 being formed only on the lower case 22. The upper case 21 and the lower case 22 may be manufactured with one side connected to each other, but this is not limited thereto, and various other configurations are possible, such as being separated and manufactured separately.

[0038] The electrode assembly 10 may have a lead 12 connected to an electrode tab 11, an insulating portion 14 disposed on a portion of the lead 12, and a housing space 231 formed in a cup portion 23 of the lower case 22, with the upper case 21 covering the electrode assembly 10 from above. An electrolyte may be poured into the housing space 231, and the housing space 231 may be sealed with a seal portion 24 formed on the edges of the upper case 21 and the lower case 22. The electrolyte is used to transport lithium ions generated by an electrochemical reaction of the electrodes when the secondary battery 1 is charged and discharged, and may include a non-aqueous organic electrolyte, which is a mixture of a lithium salt and a high-purity organic solvent, or a polymer using a polymer electrolyte. The secondary battery 1 can be manufactured using this method.

[0039] FIG. 3 is a cross-sectional view of a pouch-type battery case according to one embodiment of the present invention.

[0040] As described above, the battery case 20 according to an embodiment of the present invention can accommodate the electrode assembly 10, and can quickly extinguish a fire if it occurs in the electrode assembly 10 or if a fire spreads from the outside.

[0041] More specifically, the battery case 20 may include a barrier layer 201, an inner polymer layer 202, an outer polymer layer 203, a fire-fighting coating layer 204, and a protective layer 205. The battery case 20 may further include an adhesive layer 206.

[0042] The battery case 20 may be manufactured by drawing and molding the cup portion 23 on a pouch film. That is, the pouch film, which is the base material of the battery case 20, may be a laminate sheet including a barrier layer 201, an inner polymer layer 202, an outer polymer layer 203, a fire-extinguishing coating layer 204, and a protective layer 205.

[0043] The barrier layer 201 ensures the mechanical strength of the battery case 20, blocks the entry and exit of gases and moisture from the exterior of the secondary battery 1, and prevents leakage of the electrolyte. The barrier layer 201 includes a metal material, and is preferably made of an aluminum thin film (Al Foil). This is because aluminum can ensure a predetermined level of mechanical strength, is light in weight, and can ensure the complementation of electrochemical properties between the electrode assembly 10 and the electrolyte, heat dissipation, etc.

[0044] However, the barrier layer 201 may include various materials, including, but not limited to, one or more materials selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), and aluminum (Al).

[0045] The inner polymer layer 202 may include a first polymer material and may be located inside the barrier layer 201. Here, "inside" may mean the side closer to the electrode assembly 10 with respect to the barrier layer 201. The inner polymer layer 202 must be insulating because it is in direct contact with the electrode assembly 10, and must be corrosion-resistant because it also comes into contact with the electrolyte. Furthermore, the inner polymer layer 202 must have high sealing properties because it must completely seal the inside of the secondary battery 1 and block the movement of substances between the inside and the outside. In other words, the seal portion 24 (see FIG. 2 ) where the inner polymer layers 202 are bonded together must have excellent thermal adhesive strength.

[0046] The first polymer material contained in the inner polymer layer 202 may be 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, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. The inner polymer layer 202 preferably contains a polyolefin resin such as polypropylene (PP) or polyethylene (PE). Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, and chemical properties such as corrosion resistance, and is therefore mainly used to manufacture the inner polymer layer 202.

[0047] The outer polymer layer 203 includes a second polymer material and is located outside the barrier layer 201. The outer polymer layer 203 protects the secondary battery 1 from external friction and impact and electrically insulates the electrode assembly 10 from the outside. Here, the outside may mean the opposite side of the electrode assembly 10 with respect to the barrier layer 201.

[0048] The second polymer material contained in the outer polymer layer 203 may be 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. The outer polymer layer 203 preferably contains nylon resin or polyethylene terephthalate (PET), which has abrasion resistance and heat resistance.

[0049] Furthermore, the inner polymer layer 202 and the outer polymer layer 203 may each have a single layer structure made of one material, or a composite layer structure formed by layers of two or more materials.

[0050] On the other hand, in the present embodiment, the fire-fighting coating layer 204 may be located on the outside of the barrier layer 201. More specifically, the fire-fighting coating layer 204 may be coated on the inner surface of the outer polymer layer 203.

[0051] The fire-fighting coating layer 204 may have a plurality of capsules 204a filled with a fire-fighting agent. More specifically, the plurality of capsules 204a may be provided inside the fire-fighting coating layer 204.

[0052] The fire-extinguishing coating layer 204 may contain a binder so that it can be easily coated on the inner surface of the outer polymer layer 203. The fire-extinguishing coating layer 204 may be coated on the inner surface of the outer polymer layer 203 in a liquid state in which the plurality of capsules 204a are mixed, and then cured.

[0053] The inner surface of the outer polymer layer 203 may refer to one of the two surfaces of the outer polymer layer 203 that faces the inside of the secondary battery 1, i.e., the electrode assembly 10. A person skilled in the art would easily understand that the "inner surface" is used in the same sense for layers other than the outer polymer layer 203.

[0054] Each capsule 204a may be filled with a fire extinguishing agent, which can prevent the spread of fire inside and outside the electrode assembly 10 when the capsule 204a bursts due to high heat.

[0055] The substance used as the fire extinguishing agent is not limited, and a person skilled in the art can select an appropriate substance. As an example, the fire extinguishing agent may be a fluoroketone, more specifically, a fluoroketone having a chemical structure of CFCFC(=O)CF(CF). As another example, the fire extinguishing agent may be one or more substances selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and ammonium phosphate.

[0056] The capsule 204a may be configured to burst when it reaches a predetermined first temperature, and the material of the capsule may be selected appropriately for this purpose. For example, the first temperature may be 120 to 130 degrees Celsius, in which case the melting point of the material forming the capsule 204a may be 120 to 130 degrees Celsius. Therefore, when the fire-extinguishing coating layer 204 reaches the first temperature due to a fire that breaks out inside or outside the secondary battery 1, the capsule 204a bursts, causing the fire-extinguishing agent to leak out, thereby preventing the spread of the fire.

[0057] The capsules 204a may be microcapsules and may have a diameter of 50 μm to 300 μm. Furthermore, to prevent the overall thickness of the battery case 20 from excessively increasing, the fire-extinguishing coating layer 204 may be formed to a thickness of approximately 1 mm. In this regard, if the diameter of the capsules 204a is smaller than 50 μm, problems may arise such that the capsules 204a are difficult to manufacture, the amount of fire-extinguishing agent is reduced, and the fire-extinguishing effect is inferior. Furthermore, if the diameter of the capsules 204a is larger than 300 μm, problems may arise such that the coating of the fire-extinguishing coating layer 204 is difficult, or the thickness of the fire-extinguishing coating layer 204 is excessively increased.

[0058] The protective layer 205 may be located inside the fire-fighting coating layer 204. More specifically, the protective layer 205 may be located between the fire-fighting coating layer 204 and the barrier layer 201.

[0059] The protective layer 205 can delay the rupture of the capsules 204a of the fire-extinguishing coating layer 204 due to heat generated inside the secondary battery 1. More specifically, heat may be generated in the electrode assembly 10 (see FIG. 2) housed in the battery case 20 during charging and discharging, and the protective layer 205 can prevent the rupture of the capsules 204a of the fire-extinguishing coating layer 204 due to heat generated during normal operation of the electrode assembly 10.

[0060] Therefore, the protective layer 205 may be configured to melt when it reaches a predetermined second temperature, which may be higher than the first temperature at which the capsules 204a burst. Therefore, the material of the protective layer 205 can be selected appropriately.

[0061] For example, the second temperature may be 150 to 250 degrees Celsius, in which case the melting point of the material forming the protective layer 205 may be 150 to 250 degrees Celsius. Also, as described above, the first temperature at which the capsule 204a bursts may be 120 to 130 degrees Celsius.

[0062] Therefore, even if the protective layer 205 reaches the first temperature due to a simple increase in the internal temperature of the secondary battery 1, the capsules 204a of the fire-extinguishing coating layer 204 will not burst.

[0063] On the other hand, if a fire occurs outside the secondary battery 1, the fire-extinguishing coating layer 204 quickly reaches the first temperature, causing the capsules 204a to burst and the fire-extinguishing agent to be activated, thereby preventing the fire from spreading to the electrode assembly 10.

[0064] Furthermore, if a fire occurs inside the secondary battery 1, i.e., in the electrode assembly 10, the protective layer 205 reaches the second temperature and melts, causing the capsules 204a of the fire-extinguishing coating layer 204 to rupture and activate the fire-extinguishing agent, thereby preventing the fire from spreading to the outside of the secondary battery 1.

[0065] The protective layer 205 may have higher thermal insulation properties than the barrier layer 201 and the inner polymer layer 202 .

[0066] The thickness of the protective layer 205 may be thinner than the thickness of the fire-extinguishing coating layer 204. More specifically, the thickness of the protective layer 205 may be 1 / 100 or less of the thickness of the fire-extinguishing coating layer 204. For example, the thickness of the fire-extinguishing coating layer 204 may be approximately 1 mm, and the thickness of the protective layer 205 may be 10 μm or less. If the thickness of the protective layer 205 is greater than 10 μm, the thickness of the battery case 20 may increase excessively, which may result in a problem of a reduced energy density of the secondary battery 1.

[0067] The protective layer 205 may be formed by UV-curing an insulating solution printed on the inner surface of the fire-extinguishing coating layer 204. For example, the protective layer 205 may be formed by printing and curing a PET (Polyethylene Terephthalate) solution. However, the manufacturing process and materials of the protective layer 205 are not limited thereto and may be different as needed.

[0068] A pair of adhesive layers 206 may be provided. Of the pair of adhesive layers 206, one adhesive layer 206 may bond the barrier layer 201 and the protective layer 205, and the other adhesive layer 206 may bond the barrier layer 201 and the inner polymer layer 202. More specifically, one adhesive layer 206 may be located between the outer surface of the barrier layer 201 and the inner surface of the protective layer 205, and the other adhesive layer 206 may be located between the inner surface of the barrier layer 201 and the outer surface of the inner polymer layer 202. However, this is not intended to be limiting, and it goes without saying that the battery case 20 may include only one adhesive layer 206.

[0069] The adhesive layer 206 may be formed by curing an adhesive, but is not limited to this.

[0070] The fire-extinguishing coating layer 204 and the protective layer 205 may be included in at least a portion of the battery case 20, more specifically, in at least a portion of the cup portion 23. The fire-extinguishing coating layer 204 and the protective layer 205 may not be included in the seal portion 24 (see FIG. 2 ). This is because the fire-extinguishing coating layer 204 and the protective layer 205 are configured to extinguish a fire that breaks out in the electrode assembly 10 or to prevent a fire that breaks out outside the secondary battery 1 from spreading to the electrode assembly 10. Therefore, even if the seal portion 24 does not include the fire-extinguishing coating layer 204 and the protective layer 205, the fire-extinguishing function is not affected, and rather, the raw materials required for manufacturing the fire-extinguishing coating layer 204 and the protective layer 205 can be saved, thereby reducing manufacturing costs.

[0071] However, it goes without saying that the entire battery case 20 may include the fire-extinguishing coating layer 204 and the protective layer 205 in order to facilitate the manufacturing of the battery case 20 .

[0072] A method for manufacturing the battery case 20 according to the embodiment of the present application will be briefly described below.

[0073] The manufacturing method of the battery case 20 may include a step of coating the inner surface of the outer polymer layer 203 with the fire-extinguishing coating layer 204 provided with the capsules 204a, and a step of printing and curing an insulating solution on the inner surface of the fire-extinguishing coating layer 204 to form the protective layer 205. In this way, a composite layer in which the outer polymer layer 203, the fire-extinguishing coating layer 204, and the protective layer 205 are stacked can be prepared.

[0074] The manufacturing method of the battery case 20 may further include a step of bonding a composite protective layer 205 to the outer surface of the barrier layer 201, and bonding an inner polymer layer 202 to the inner surface of the barrier layer 201. Here, adhesive may be applied between the barrier layer 201 and the protective layer 205, and between the barrier layer 201 and the inner polymer layer 202, to form adhesive layers 206.

[0075] This allows the pouch film, which is the base material of the battery case 20, to be prepared, and the battery case 20 can be manufactured by forming the cup portion 23 (see FIG. 1) in the pouch film.

[0076] FIG. 4 is a cross-sectional view of a battery case according to another embodiment of the present invention.

[0077] Hereinafter, the same content as in the above-described embodiment will be omitted, and the differences will be mainly described.

[0078] In the battery case 20′ according to the embodiment of the present application, the fire-extinguishing coating layer 204 may be located inside the barrier layer 201. More specifically, the fire-extinguishing coating layer 204 may be coated on the inner surface of the barrier layer 201.

[0079] The fire-extinguishing coating layer 204 may contain a binder to facilitate coating on the inner surface of the barrier layer 201. The fire-extinguishing coating layer 204 may be formed by coating the inner surface of the barrier layer 201 with a liquid mixture of a plurality of capsules 204a, and then curing the mixture. Therefore, an adhesive layer may not be provided between the barrier layer 201 and the fire-extinguishing coating layer 204.

[0080] The protective layer 205 may be located inside the fire-fighting coating layer 204. More specifically, the protective layer 205 may be located between the fire-fighting coating layer 204 and the inner polymer layer 202.

[0081] Alternatively, a pair of adhesive layers 206 may be provided. Of the pair of adhesive layers 206, one adhesive layer 206 may bond the barrier layer 201 and the outer polymer layer 203, and the other adhesive layer 206 may bond the protective layer 205 and the inner polymer layer 202. More specifically, one adhesive layer 206 may be located between the outer surface of the barrier layer 201 and the inner surface of the outer polymer layer 203, and the other adhesive layer 206 may be located between the inner surface of the protective layer 205 and the outer surface of the inner polymer layer 202. However, this is not limiting, and it goes without saying that the battery case 20 may include only one adhesive layer 206.

[0082] A method for manufacturing the battery case 20' according to the embodiment of the present invention will be briefly described below.

[0083] The manufacturing method of the battery case 20′ may include a step of coating the inner surface of the barrier layer 201 with the fire-extinguishing coating layer 204 provided with the capsules 204a, and a step of printing and curing an insulating solution on the inner surface of the fire-extinguishing coating layer 204 to form the protective layer 205. In this way, a composite layer in which the barrier layer 201, the fire-extinguishing coating layer 204, and the protective layer 205 are stacked can be prepared.

[0084] The manufacturing method of the battery case 20′ may further include a step of bonding a protective layer 205 of the composite layer to the outer surface of the inner polymer layer 202, and bonding an outer polymer layer 203 to the outer surface of the barrier layer 201 of the composite layer. Here, adhesive may be applied between the inner polymer layer 202 and the protective layer 205, and between the barrier layer 201 and the outer polymer layer 203, to form adhesive layers 206.

[0085] This allows the pouch film, which is the base material of the battery case 20', to be prepared, and the battery case 20' can be manufactured by forming the cup portion 23 (see FIG. 1) in the pouch film.

[0086] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations may be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0087] Therefore, the embodiments disclosed in the present invention are for illustrative purposes, not for limiting the technical idea of ​​the present invention, and such embodiments do not limit the scope of the technical idea of ​​the present invention.

[0088] The scope of protection of the present invention should be interpreted by the appended claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of rights of the present invention. [Explanation of symbols]

[0089] 1 Secondary battery 10 Electrode assembly 20 Pouch-type battery case 23 Cup section 24 Seal part 201 Barrier Layer 202 Inner polymer layer 203 outer polymer layer 204 Fire-extinguishing coating layer 204a Capsule 205 Protective layer 206 Adhesive layer

Claims

1. a barrier layer having a metallic material; an inner polymer layer positioned inside the barrier layer and having a first polymer material; an outer polymer layer located outside the barrier layer and comprising a second polymer material; a fire-extinguishing coating layer positioned on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent; a protective layer located inside the fire-extinguishing coating layer, the capsules of the fire-extinguishing coating layer rupture at a first temperature; The pouch-type battery case, wherein the protective layer melts at a second temperature higher than the first temperature.

2. the fire-fighting coating layer is located outside the barrier layer; The pouch-type battery case according to claim 1 , wherein the protective layer is located between the fire-extinguishing coating layer and the barrier layer.

3. the fire-fighting coating layer is located inside the barrier layer; The pouch-type battery case according to claim 1 , wherein the protective layer is located between the fire-extinguishing coating layer and the inner polymer layer.

4. A barrier layer having a metallic material; an inner polymer layer positioned inside the barrier layer and having a first polymer material; an outer polymer layer located outside the barrier layer and comprising a second polymer material; a fire-extinguishing coating layer positioned on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent; a protective layer located inside the fire-extinguishing coating layer, the capsules of the fire-extinguishing coating layer rupture at 120 to 130 degrees Celsius; The pouch-type battery case, wherein the protective layer melts at 150 to 250 degrees.

5. 3. The pouch-type battery case according to claim 1, wherein the protective layer has a thickness smaller than that of the fire-extinguishing coating layer.

6. 3. The pouch-type battery case according to claim 1, wherein the thickness of the protective layer is 1 / 100 or less of the thickness of the fire-extinguishing coating layer.

7. 3. The pouch-type battery case according to claim 1, wherein the capsules of the fire-extinguishing coating layer have a diameter of 50 μm to 300 μm.

8. 3. The pouch-type battery case according to claim 1, wherein the fire-extinguishing agent filled in the capsules of the fire-extinguishing coating layer includes a fluoroketone.

9. an electrode assembly; a pouch-type battery case in which the electrode assembly is housed, At least a portion of the pouch-type battery case is a barrier layer having a metallic material; an inner polymer layer positioned inside the barrier layer and having a first polymer material; an outer polymer layer located outside the barrier layer and comprising a second polymer material; a fire-extinguishing coating layer positioned on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent; a protective layer located inside the fire-extinguishing coating layer, the capsules of the fire-extinguishing coating layer rupture at a first temperature; The protective layer melts at a second temperature higher than the first temperature.

10. An electrode assembly; a pouch-type battery case in which the electrode assembly is housed, At least a portion of the pouch-type battery case is a barrier layer having a metallic material; an inner polymer layer positioned inside the barrier layer and having a first polymer material; an outer polymer layer located outside the barrier layer and comprising a second polymer material; a fire-extinguishing coating layer positioned on one side of the barrier layer and having a plurality of capsules filled with a fire-extinguishing agent; a protective layer located inside the fire-extinguishing coating layer, The sealed portion of the pouch-type battery case does not include the fire-extinguishing coating layer or the protective layer.

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