Case for secondary battery, secondary battery, module and device comprising same

Abstract

According to the present invention, a case for a secondary battery that accommodates an electrode assembly, wherein the case comprises a lower member, an upper member disposed above the lower member, and a sealing portion in which the lower member and the upper member are fused to seal the case, wherein the sealing portion comprises a first sealing portion having an electrode terminal connected to the electrode assembly and a second sealing portion which is the remaining area excluding the first sealing portion, and wherein the case comprises a polymer resin layer formed at the edge of the first sealing portion and a reinforcing layer surrounding the polymer resin layer, thereby providing a case for a secondary battery with improved water resistance, insulation, and mechanical properties, a secondary battery, a module, and a device including the same.

Description

Technology Field

[0001] The present invention relates to a case for a secondary battery comprising a polymer resin layer formed at the edge of a sealing portion having an electrode terminal connected to an electrode assembly and a reinforcing layer surrounding the polymer resin layer, a secondary battery, a module, and a device comprising the same. Background Technology

[0003] With the advancement of the electronics, telecommunications, and space industries, the demand for secondary batteries as an energy source is rapidly increasing. In particular, as the importance of global eco-friendly policies is emphasized, the electric vehicle market is growing exponentially, and active research and development on secondary batteries is being conducted both domestically and internationally.

[0004] Generally, a secondary battery is manufactured by housing an electrode assembly containing a negative electrode, a positive electrode, and a separator in a secondary battery case, cutting the portion where the electrode terminals are located to process the case into a required shape, and sealing the edges of the case. FIG. 1 schematically shows a secondary battery case housing a conventional electrode assembly. Referring to FIG. 1, a secondary battery case (100) housing an electrode assembly (110) includes upper and lower members (120), electrode terminals (140, 141) connected to the electrode assembly (110), and a sealing portion (130) in which the upper and lower members (120) are fused to seal the case (120).

[0005] FIG. 2 schematically shows a cross-section of the case of FIG. 1 cut at AA'. Referring to FIG. 1 and 2, the edge of the sealing portion where the electrode terminal is located has a laminated structure of a polyolefin resin layer (11c, 12c), a metal layer (11b, 12b), and a protective layer (11a, 12a), and the polyolefin resin layer (11c, 12c), the metal layer (11b, 12b), and the protective layer (11a, 12a) are exposed to the external environment. The polyolefin resin layer (11c, 12c) is vulnerable to moisture compared to the metal layer (11b, 12b) and the protective layer (11a, 12a), and the metal layer (11b, 12b) has a problem of short circuit occurring with the electrode terminal (141) due to its electrical characteristics.

[0006] In addition, although a method was devised to change the bonding form of the sealing part to improve water resistance and insulation, there was a problem that the volume or weight of the case (100) was deformed, and in particular, a problem remained that the battery performance rapidly deteriorated due to a venting phenomenon in which the seal of the case (100) was released by an external impact. The problem to be solved

[0008] The present invention provides a case for a secondary battery capable of improving battery performance by forming a polymer resin layer and a reinforcing layer surrounding the polymer resin layer at the edge of a sealing portion having an electrode terminal connected to an electrode assembly, a secondary battery including the same, a module, and a device. means of solving the problem

[0010] A case for a secondary battery according to the present invention is a case for a secondary battery that accommodates an electrode assembly, wherein the case comprises a lower member, an upper member disposed on the upper side of the lower case, and a sealing portion in which the lower member and the upper member are fused to seal the case, wherein the sealing portion comprises a first sealing portion having an electrode terminal connected to the electrode assembly and a second sealing portion which is the remaining area excluding the first sealing portion, and comprises a polymer resin layer formed at the edge of the first sealing portion and a reinforcing layer surrounding the polymer resin layer.

[0011] According to the embodiment, the edge of the first sealing portion may not be exposed to the outside by the reinforcing layer.

[0012] According to an embodiment, the first sealing portion includes a first-1 sealing portion present in the area where the electrode terminal protrudes and a first-2 sealing portion which is the remaining area excluding the area where the electrode terminal protrudes, and the edges of the first-1 sealing portion and the first-2 sealing portion may not be exposed to the outside by the reinforcing layer.

[0013] According to an embodiment, the edge of the first sealing portion may be laminated with a polyolefin resin layer, a metal layer, and a protective layer.

[0014] According to an example, the polyolefin-based resin layer may be coated by the polymer resin layer.

[0015] According to an example, the polymer resin layer may include a thermosetting resin.

[0016] According to the example, the polymer resin layer may include one or more selected from the group consisting of silicone resin and epoxy resin.

[0017] According to the example, the thickness of the polymer resin layer may be 10 μm to 300 μm.

[0018] According to an example, the reinforcing layer may include one or more selected from the group consisting of silicone resin, epoxy resin, and rubber-based resin.

[0019] According to the example, the rubber-based resin may include one or more selected from the group consisting of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber (IIR), ethylene-propylene rubber (EPDM), chlorosulfonated polyethylene rubber (CSM), acrylic rubber (ACM), and fluororubber (FPM).

[0020] According to the examples, the resin included in the polymer resin layer and the resin included in the reinforcing layer may have different vitrification temperatures, thermal expansion coefficients, or mechanical expansion coefficients.

[0021] According to an embodiment, the reinforcing layer may be formed as a single layer or a plurality of layers of two or more.

[0022] According to the example, the thickness of the reinforcing layer may be 10 μm to 800 μm.

[0023] A secondary battery according to the present invention comprises an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a case for the secondary battery of the present invention that accommodates the electrode assembly.

[0024] The module according to the present invention includes the secondary battery of the present invention as a unit cell.

[0025] The device according to the present invention includes the module of the present invention as a power source. Effects of the invention

[0027] The case for a secondary battery according to the present invention has a polymer resin layer and a reinforcing layer formed at the edge of a sealing portion where an electrode terminal connected to an electrode assembly is located, thereby having the effect of preventing the polyolefin-based resin layer located at the edge from being exposed to the outside.

[0028] In addition, the case for a secondary battery according to the present invention has the effect of reducing gas generation caused by the reaction between moisture and the electrolyte by protecting the polyolefin-based resin layer from the external environment, thereby reducing the amount of moisture penetrating through the polyolefin-based resin layer.

[0029] In addition, the secondary battery case according to the present invention forms a polymer resin layer and a reinforcing layer locally only at the edges of the sealing portion, thereby having the effect of improving water resistance without significantly affecting the volume and weight of the secondary battery case.

[0030] In addition, the case for a secondary battery according to the present invention has the effect of insulating the metal layer located at the edge and the electrode terminal by forming a polymer resin layer and a reinforcing layer at the edge of the sealing portion.

[0031] In addition, the case for a secondary battery according to the present invention has a reinforcing layer formed to surround a polymer resin layer at the edge of the sealing portion, thereby having the effect of improving not only water resistance and insulation but also mechanical properties.

[0032] In addition, the case for a secondary battery according to the present invention can delay the venting phenomenon in which the seal of the case is released due to enhanced water resistance, insulation, and mechanical properties, thereby having the effect of maintaining the performance of the secondary battery including the case for a long period of time. Brief explanation of the drawing

[0034] Figure 1 schematically shows a case for a secondary battery that accommodates a conventional electrode assembly. Figure 2 schematically shows a cross-section of the case of Figure 1 cut at AA'. FIG. 3 schematically shows a case for a secondary battery that accommodates an electrode assembly according to an embodiment of the present invention. Figure 4 schematically shows a cross-section of the case of Figure 3 cut at BB'. Figure 5 schematically shows a cross-section of the case of Figure 3 cut at CC'. FIG. 6 schematically shows a case for a secondary battery having a plurality of reinforcing layers formed thereon according to an embodiment of the present invention. FIG. 7 schematically shows a case for a secondary battery having a plurality of reinforcing layers formed thereon according to another embodiment of the present invention. Figure 8 schematically shows a cross-section of the case of Figure 3 cut at DD'. Specific details for implementing the invention

[0035] The structural or functional descriptions of the embodiments disclosed in this specification or application are merely illustrative for the purpose of explaining embodiments according to the technical concept of this disclosure. Embodiments according to the technical concept of this invention may be implemented in various forms other than those disclosed in this specification or application, and the technical concept of this invention is not to be interpreted as being limited to the embodiments described in this specification or application.

[0037] Hereinafter, a case for a secondary battery according to the present invention, a secondary battery including the same, a module, and a device will be described in detail.

[0039] The present invention relates to a case for a secondary battery that accommodates an electrode assembly, wherein the case comprises a lower member, an upper member disposed above the lower member, and a sealing portion in which the lower member and the upper member are fused to seal the case, wherein the sealing portion comprises a first sealing portion having an electrode terminal connected to the electrode assembly and a second sealing portion which is the remaining area excluding the first sealing portion, and wherein the case comprises a polymer resin layer formed at the edge of the first sealing portion and a reinforcing layer surrounding the polymer resin layer.

[0041] FIG. 3 schematically shows a case for a secondary battery that accommodates an electrode assembly according to an embodiment of the present invention.

[0042] Referring to FIG. 3, a case (200) for a secondary battery according to an embodiment of the present invention accommodates an electrode assembly (210), and the case (200) includes a lower member (220), an upper member (220) disposed above the lower member, and a sealing portion in which the lower member (220) and the upper member (220) are fused to seal the case (200). The sealing portion includes a first sealing portion (231) in which an electrode terminal (240, 241) connected to the electrode assembly (210) exists, and a second sealing portion (230) which is the remaining area excluding the first sealing portion (231).

[0043] Referring to FIG. 3, the electrode terminals (240, 241) connected to the electrode assembly (210) housed in the case (200) are shown as being located on different sides, but are not limited thereto, and the electrode terminals (240, 241) may be located on the same side. For example, the electrode terminals (240, 241) are a negative terminal and a positive terminal, and the negative terminal and the positive terminal may be located on different sides or on the same side. The first sealing portion (231) and the second sealing portion (230) may be formed by compressing or heat-fusion the edges of the upper member (220) and the lower member (220).

[0045] Figure 4 schematically shows a cross-section of the case of Figure 3 cut at BB'.

[0046] Referring to FIGS. 2 to 4, the edge of the first sealing portion (231) may not be exposed to the outside by the reinforcing layer (262). For example, the first sealing portion (231) includes a first-1 sealing portion (251) located at the protruding portion of the electrode terminal (241) and a first-2 sealing portion (252) which is the remaining area excluding the protruding portion of the electrode terminal (241), and the edge of the first-1 sealing portion (251) and the first-2 sealing portion (252) may not be exposed to the outside by the reinforcing layer (262). Conventional cases (100) had a problem in which the edge of the sealing portion where the electrode terminal (141) is located was exposed to the external environment, making it vulnerable to moisture or causing an electrical short circuit. However, the case (200) according to the present invention has a polymer resin layer and a reinforcing layer (262) surrounding the polymer resin layer formed at the edge, and the edge is not exposed to the outside by the reinforcing layer (262), thereby improving water resistance, insulation, and mechanical properties. The edge may refer to an area exposed to the outside as an end, cross-section, or cut surface of the first sealing part (231).

[0048] Figure 5 schematically shows a cross-section of the case of Figure 3 cut at CC'.

[0049] Referring to FIGS. 3 to 5, the edge of the first sealing portion (231) may have a structure in which a polyolefin resin layer (21c, 22c), a metal layer (21b, 22b), and a protective layer (21a, 22a) are laminated.

[0050] The above protective layer (21a, 22a) can protect the electrode assembly (210) housed in the case (200) from the external environment. The above protective layer (21a, 22a) may include one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate, and nylon film, but is not limited thereto.

[0051] The metal layers (21b, 22b) can prevent moisture from penetrating into the case (200). The metal layers (21b, 22b) may include one or more selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), copper (Cu), aluminum (Al), and alloys, but are not limited thereto.

[0052] The polyolefin resin layers (21c, 22c) can be fused to seal the case (200). For example, the polyolefin resin layers (21c, 22c) may be in the form where the polyolefin resin layer (21c) included in the upper member (220) and the polyolefin resin layer (22c) included in the lower member (220) are bonded by a heat fusion method. The polyolefin resin layers (21c, 22c) may include one or more selected from the group consisting of polyethylene and polypropylene, but are not limited thereto. The polyolefin resin layers (21c, 22c) have a problem of being vulnerable to moisture penetration compared to the metal layers (21b, 22b) and the protective layers (21a, 22a). Accordingly, when the polyolefin resin layer (21c, 22c) is exposed to an external environment, moisture and electrolyte that have penetrated through the polyolefin resin layer (21c, 22c) may react, thereby degrading the performance of the battery or increasing gas generation within the case (200).

[0054] To solve this problem, the case (200) according to the present invention includes a polymer resin layer (261) formed on the edge of the first sealing portion (231). The polyolefin resin layer (21c, 22c) may be covered by the polymer resin layer (261). By covering the polyolefin resin layer (21c, 22c) with the polymer resin layer (261), the polyolefin resin layer (21c, 22c) is prevented from being exposed to the external environment, thereby reducing the phenomenon of battery performance degradation caused by leakage of the electrolyte present inside the case (200) due to moisture penetration. In addition, when the battery is used for a long period, there is an effect of delaying the venting phenomenon in which the seal of the case (200) is released due to gas generated by the reaction between moisture and the electrolyte.

[0055] The polymer resin layer (261) may include a thermosetting resin. For example, the polymer resin layer (261) may include one or more selected from the group consisting of silicone resin and epoxy resin. The silicone resin and epoxy resin have excellent water resistance and insulation properties, which can reduce the amount of moisture penetrating through the polyolefin resin layer (21c, 22c) and prevent the metal layer (21b, 22b) from coming into contact with the electrode terminal (241), thereby preventing an electrical short circuit.

[0056] The thickness (T) of the polymer resin layer (261) may be 10 μm to 300 μm, 10 μm to 250 μm, or 20 μm to 200 μm. When the thickness range is satisfied, moisture penetration can be effectively blocked without reducing the processability of the case (200).

[0057] The polymer resin layer (261) can prevent moisture from penetrating through the polyolefin resin layer (21c, 22c), but the physical properties of the polymer resin layer (261) may deteriorate when the battery is used for a long period. In addition, the polymer resin layer (261) lacks mechanical properties, so a problem may occur in which the polymer resin layer (261) detaches from the polyolefin resin layer (21c, 22c) due to an impact applied from the outside.

[0059] To solve these problems, the case (200) according to the present invention includes a reinforcing layer (262) that surrounds the polymer resin layer (261) formed at the edge of the first sealing portion (231). The reinforcing layer (262) can improve the mechanical properties of the polymer resin layer (261), thereby delaying the phenomenon in which the polymer resin layer (261) detaches from the polyolefin resin layer (21c, 22c) due to an impact applied from the outside. In addition, the reinforcing layer (262) can improve the water resistance of the polymer resin layer (261), thereby delaying the venting phenomenon in which the seal of the case (200) is released due to gas generated by the reaction between moisture and the electrolyte, even when the battery is used for a long period of time. In addition, the reinforcing layer (262) can supplement the insulation of the polymer resin layer (261), thereby preventing the metal layer (21b, 22b) from coming into contact with the electrode terminal (241), which can more effectively prevent the phenomenon of an electrical short circuit.

[0060] The reinforcing layer (262) may include one or more selected from the group consisting of silicone resin, epoxy resin, and rubber-based resin. The silicone resin and epoxy resin may be the same or different from the silicone resin and epoxy resin included in the polymer resin layer (261). The silicone resin and epoxy resin may complement the water resistance and insulation properties of the polymer resin layer (261). The rubber-based resin may include one or more selected from the group consisting of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber (IIR), ethylene-propylene rubber (EPDM), chlorosulfonated polyethylene rubber (CSM), acrylic rubber (ACM), and fluororubber (FPM). The above rubber-based resin has excellent mechanical properties, so it can delay the phenomenon in which the polymer resin layer (261) is detached from the polyolefin-based resin layer (21c, 22c) due to an external impact.

[0061] The resin contained in the polymer resin layer (261) and the resin contained in the reinforcing layer (262) may have different vitrification temperatures, thermal expansion coefficients, or mechanical expansion coefficients. When the physical properties of the resin contained in the polymer resin layer (261) and the resin contained in the reinforcing layer (262) are different, the degree of deformation of the resins varies depending on the pressure and temperature applied from the outside, so that the water resistance, insulation, and mechanical properties of the polymer resin layer (261) and the reinforcing layer (262) can be realized in a mutually complementary manner.

[0063] FIGS. 6 and 7 schematically illustrate a case for a secondary battery having a plurality of reinforcing layers formed therein according to an embodiment of the present invention. Referring to FIGS. 6 and 7, the reinforcing layer (262) may be formed as a single layer or as a plurality of layers, two or more. FIGS. 6 and 7 illustrate various forms of the reinforcing layer (262) formed as two layers on the polymer resin layer (261), but are not limited thereto, and the reinforcing layer (262) may be formed as three layers on the polymer resin layer (261) as needed. When a plurality of reinforcing layers (262) are formed on the polymer resin layer (261), improved mechanical properties can be achieved, and the performance of the secondary battery including the case can be maintained for a long period of time.

[0064] The thickness (T') of the reinforcing layer (262) may be 10 μm to 800 μm, 10 μm to 700 μm, or 20 μm to 500 μm. When the thickness range is satisfied, moisture penetration can be effectively blocked without deterioration of the processability and mechanical properties of the case.

[0066] FIG. 8 schematically shows a cross-section of the case of FIG. 3 cut at DD'. Referring to FIG. 3, 4 and 8, the polymer resin layer (261) and the reinforcing layer (262) are formed at the edge of the first sealing portion (231) where the electrode terminal (241) is located. For example, the polymer resin layer (261) and the reinforcing layer (262) may be formed on the upper and lower portions of the electrode terminal (241), and may be formed on the upper and lower portions of the sealant placed on the electrode terminal (241). By forming the polymer resin layer (261) and the reinforcing layer (262) at the edge of the first sealing portion (231) where the electrode terminal (241) is located, the occurrence of a short circuit due to contact between the electrode terminal (241) located in the first sealing portion (251) and the metal layer (21b, 22b) located at the edge of the first sealing portion (252) can be prevented.

[0068] A secondary battery according to the present invention comprises an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a case for a secondary battery according to the present invention that accommodates the electrode assembly.

[0070] The above positive and negative electrodes may each include a current collector and an active material layer disposed on the current collector. For example, the positive electrode may include a positive current collector and a positive active material layer, and the negative electrode may include a negative current collector and a negative active material layer.

[0071] The above current collector may include a known conductive material within a range that does not cause a chemical reaction within the lithium secondary battery. For example, the above current collector may include any one of stainless steel, nickel (Ni), aluminum (Al), titanium (Ti), copper (Cu), and alloys thereof, and may be provided in various forms such as a film, sheet, or foil.

[0072] The above active material layer includes an active material. For example, the positive electrode active material layer may include a positive electrode active material, and the negative electrode active material layer may include a negative electrode active material.

[0073] The above-mentioned positive electrode active material may be a material capable of inserting and extracting lithium (Li) ions. The above-mentioned positive electrode active material may be a lithium metal oxide. For example, the above-mentioned positive electrode active material may be one of a lithium manganese-based oxide, a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium nickel-manganese-based oxide, a lithium nickel-cobalt-manganese-based oxide, a lithium nickel-cobalt-aluminum-based oxide, a lithium iron-based compound, a lithium manganese-based compound, a lithium cobalt-based compound, and a lithium vanadium-based compound, but is not necessarily limited to specific examples.

[0074] The above-mentioned negative electrode active material may be a material capable of absorbing and extracting lithium ions. For example, the above-mentioned negative electrode active material may be any one of carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers, lithium alloys, silicon (Si), and tin (Sn). According to the embodiments, the negative electrode active material may be natural graphite or artificial graphite, but is not limited to specific examples.

[0075] The above anode and cathode may each further include a binder and a conductive material.

[0076] The above binder can improve mechanical stability by mediating the bonding between the current collector and the active material layer. For example, the binder may be an organic binder or a water-based binder, and may be used together with a thickener such as carboxymethyl cellulose (CMC). For example, the organic binder may be any one of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, and polymethylmethacrylate, and the water-based binder may be styrene-butadiene rubber (SBR), but is not necessarily limited thereto.

[0077] The above conductive material can improve the electrical conductivity of a lithium secondary battery. The conductive material may include a metal-based material. The above conductive material may include a conventional carbon-based conductive material. For example, the conductive material may include any one of graphite, carbon black, graphene, and carbon nanotubes. Preferably, the conductive material may include carbon nanotubes.

[0078] The above separator is interposed between the anode and the cathode. The separator can be configured to prevent an electrical short circuit between the anode and the cathode and to generate a flow of ions.

[0079] For example, the separator may include a porous polymer film or a porous nonwoven fabric. The porous polymer film may be composed of a single layer or multiple layers including polyolefin-based polymers such as ethylene polymer, propylene polymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer. The porous nonwoven fabric may include high-melting-point glass fibers or polyethylene terephthalate fibers. However, it is not limited thereto, and depending on the embodiment, the separator may be a high-heat-resistant separator (CCS; Ceramic Coated Separator) including ceramic.

[0081] The electrode assembly comprises the anode, cathode, and separator. A plurality of the electrode assemblies may be provided and sequentially stacked within a case for a secondary battery according to the present invention. For example, a plurality of the electrode assemblies may be provided and may be wound, laminated, folded, or zigzag stacked.

[0082] The above electrode assembly can be provided together with an electrolyte to manufacture a secondary battery. The electrolyte may be a non-aqueous electrolyte. The electrolyte may include a lithium salt and an organic solvent. For example, the organic solvent may include one or more selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), dipropyl carbonate (DPC), vinylene carbonate (VC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, gamma-butyrolactone, propylene sulfide, and tetrahydrofuran.

[0084] The module according to the present invention includes the secondary battery according to the present invention as a unit cell. Additionally, the device according to the present invention includes the module according to the present invention as a power source. The case for the secondary battery according to the present invention can reduce the amount of moisture penetrating into the case, can insulate the space between the metal layer on the cut surface and the electrode terminal, and can improve mechanical properties, thereby having the effect of maintaining the performance of the secondary battery including the case for a long period. Accordingly, the module including the secondary battery as a unit cell and the device including the module as a power source can have improved output characteristics, capacity, and stability. Explanation of the symbols

[0086] 21a, 22a: Protective layer 21b, 22b: Metal layer 21c, 22c: Polyolefin resin layer 200: Case for secondary batteries 210: Electrode assembly 220: Upper and lower members 230: Second sealing section 231: 1st sealing section 240, 241: Electrode terminals 251: Section 1-1 Sealing Section 252: 1st-2nd Sealing Section 261: Polymer resin layer 262: Reinforcement layer

Claims

Claim 1 A case for a secondary battery that accommodates an electrode assembly, wherein the case comprises: a lower member; an upper member disposed above the lower member; and a sealing portion in which the lower member and the upper member are fused to seal the case; wherein the sealing portion comprises a first sealing portion having an electrode terminal connected to the electrode assembly and a second sealing portion which is the remaining area excluding the first sealing portion, wherein the edge of the first sealing portion is laminated with a polyolefin resin layer, a metal layer, and a protective layer, and comprises a polymer resin layer formed at the edge of the first sealing portion and a reinforcing layer surrounding the polymer resin layer, wherein the polyolefin resin layer and the metal layer are covered by the polymer resin layer and do not come into contact with the reinforcing layer, and the reinforcing layer surrounds the polymer resin layer while coming into contact with the protective layer. Claim 2 delete Claim 3 A case for a secondary battery according to claim 1, wherein the first sealing portion comprises a first-1 sealing portion present in the portion where the electrode terminal protrudes and a first-2 sealing portion in the remaining area excluding the portion where the electrode terminal protrudes, and the edges of the first-1 sealing portion and the first-2 sealing portion are not exposed to the outside by the reinforcing layer. Claim 4 delete Claim 5 delete Claim 6 A case for a secondary battery according to claim 1, wherein the polymer resin layer comprises a thermosetting resin. Claim 7 A case for a secondary battery according to claim 1, wherein the polymer resin layer comprises one or more selected from the group consisting of silicone resin and epoxy resin. Claim 8 A case for a secondary battery according to claim 1, wherein the thickness of the polymer resin layer is 10 μm to 300 μm. Claim 9 A case for a secondary battery according to claim 1, wherein the reinforcing layer comprises one or more selected from the group consisting of silicone resin, epoxy resin, and rubber-based resin. Claim 10 A case for a secondary battery according to claim 9, wherein the rubber-based resin comprises one or more selected from the group consisting of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber (IIR), ethylene-propylene rubber (EPDM), chlorosulfonated polyethylene rubber (CSM), acrylic rubber (ACM), and fluororubber (FPM). Claim 11 A case for a secondary battery according to claim 1, wherein the resin included in the polymer resin layer and the resin included in the reinforcing layer have different vitrification temperatures, thermal expansion coefficients, or mechanical expansion coefficients. Claim 12 A case for a secondary battery according to claim 1, wherein the reinforcing layer is formed as a single layer or a plurality of layers of two or more. Claim 13 A case for a secondary battery according to claim 1, wherein the thickness of the reinforcing layer is 10 μm to 800 μm. Claim 14 A secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; and a case for a secondary battery according to claim 1 that accommodates the electrode assembly. Claim 15 A module comprising a secondary battery according to Clause 14 as a unit cell. Claim 16 A device comprising a module according to paragraph 15 as a power source.

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