Title of the invention: Case for lithium metal secondary battery, lithium metal secondary battery including the same, and manufacturing method thereof Technical field [One] The present invention relates to a case for a lithium metal secondary battery, a lithium metal secondary battery including the same, and a manufacturing method thereof. [2] This application is an application for claiming priority for Korean Patent Application No. 10-2018-0052652 filed on May 08, 2018, and all contents disclosed in the specification and drawings of the application are incorporated herein by reference. Background [3] Recently, interest in energy storage technology is increasing. As the fields of application to mobile phones, camcorders, notebook PCs, and even electric vehicles are expanded, efforts for research and development of electrochemical devices are increasingly being materialized. Electrochemical devices are the field that is receiving the most attention in this respect, and the development of secondary batteries capable of charging and discharging among them is the focus of interest, and in recent years, new electrodes to improve capacity density and specific energy in developing such batteries It is proceeding with research and development on the design of and battery. [4] Among the currently applied secondary batteries, the lithium secondary battery developed in the early 1990s has the advantage of having a higher operating voltage and significantly higher energy density than conventional batteries such as Ni-MH, Ni-Cd, and sulfuric acid-lead batteries using aqueous electrolyte solutions. Is in the limelight. [5] Lithium metal, carbon-based material, silicon, and the like are used as the negative active material of such a lithium secondary battery, and a battery using lithium metal as a negative active material is called a lithium metal secondary battery. Since such lithium metal secondary batteries have the advantage of obtaining the highest energy density, continuous research is being conducted. [6] However, lithium metal, which is used as an anode active material in lithium metal secondary batteries, has soft ductility and low releasability. Therefore, when the penetrating member inserted from the outside passes through the battery while using the battery, that is, in the nail safety test, ignition or short circuit may occur. Therefore, a lithium metal battery generally has a problem in that nail safety is weaker than a lithium ion battery including graphite, which is generally used as an anode active material. Detailed description of the invention Technical challenge [7] Accordingly, a problem to be solved by the present invention is to provide a case for a lithium metal secondary battery having excellent nail safety, a lithium metal secondary battery including the same, and a manufacturing method thereof. [8] Another problem to be solved by the present invention is to provide a lithium metal secondary battery with improved releasability for a through member inserted from the outside. [9] Another problem to be solved by the present invention is to provide a lithium metal secondary battery in which a short circuit is prevented. [10] It will be readily appreciated that other objects and advantages of the present invention can be realized by means or methods described in the claims, and combinations thereof. Means of solving the task [11] The present invention provides a case for a lithium metal secondary battery to solve the above problems. [12] A first embodiment of the present invention, a battery packaging material; At least one releasable capsule attached to at least a part or all of the inner surface of the casing to cover the inner surface of the casing and a release solution supported on the releasable capsule; and [13] The releasable capsule includes a capsule film and a capsule inner space surrounded by the capsule film, [14] The release solution is supported in the inner space of the capsule, [15] The release solution relates to a case for a lithium metal secondary battery containing a release agent and a solvent. [16] In the second embodiment of the present invention, in the first embodiment, [17] The release agent is a vinyl acetate resin, a vinyl chloride resin, a urethane resin, a chlorinated rubber resin, a phthalic acid resin, an alkyd resin, an epoxy resin, a phenol resin, a melanin resin, an acrylic resin, a fluorine resin, a silicone resin, a metal It relates to an acrylate-based resin, a rosin-based resin, or a case for a lithium metal battery containing two or more of them. [18] In the third embodiment of the present invention, in the second embodiment, [19] The fluorine-based resin relates to a case for a lithium metal secondary battery containing fluorosilane, perfluoropolyether, fluoroacrylate, perfluoromethacrylate, or two or more of them. [20] In the fourth embodiment of the present invention, in any one of the first to third embodiments, [21] The releasable capsule includes a polymer resin as a capsule film component, and the capsule film is ruptured by a penetrating member inserted from the outside to release the release solution carried in the capsule inner space will be. [22] In the fifth embodiment of the present invention, in the fourth embodiment, [23] The polymer resin is polyolefin, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, or It relates to a case for a lithium metal secondary battery containing two or more of these. [24] In the sixth embodiment of the present invention, in any one of the first to fifth embodiments, [25] The content of the release agent is 0.1 to 80% by weight based on the total weight of the release solution, relates to a case for a lithium metal battery. [26] In the seventh embodiment of the present invention, in any one of the first to sixth embodiments, [27] The releasable capsule relates to a case for a lithium metal secondary battery that has any one of a foam type, a matrix type, and a pocket type. [28] The present invention provides a lithium metal secondary to solve the above problems. [29] The eighth embodiment of the present invention, [30] Battery case; And [31] Includes; an electrode assembly charged to the battery case, [32] The electrode assembly includes a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode, and the negative electrode includes lithium metal as a negative electrode active material, [33] The battery case relates to a lithium metal secondary battery according to any one of the first to seventh embodiments. [34] The present invention provides a method of manufacturing a lithium metal secondary battery for solving the above problems. [35] The ninth embodiment of the present invention, [36] (S1) preparing a release solution in which a release agent is dispersed in a solvent; [37] (S2) preparing a releasable capsule carrying the release solution; [38] (S3) attaching one or more of the releasable capsules to a part or all of the inner surface of the battery casing to prepare a battery case in which the inner surface of the battery casing is covered by the releasable capsule; And [39] (S4) charging an electrode assembly containing lithium metal as a negative electrode active material in the battery case; and a method of manufacturing a lithium metal secondary battery including. [40] In the tenth embodiment of the present invention, in the ninth embodiment, [41] The release agent is a vinyl acetate resin, a vinyl chloride resin, a urethane resin, a chlorinated rubber resin, a phthalic acid resin, an alkyd resin, an epoxy resin, a phenol resin, a melanin resin, an acrylic resin, a fluorine resin, a silicone resin, a metal It relates to a method of manufacturing a lithium metal secondary battery containing an acrylate resin, a rosin resin, or two or more of them. [42] In the eleventh embodiment of the present invention, in the tenth embodiment, [43] The fluorine-based resin relates to a method of manufacturing a lithium metal secondary battery that includes fluorosilane, perfluoropolyether, fluoroacrylate, perfluoromethacrylate, or two or more of them. [44] In the twelfth embodiment of the present invention, in any one of the ninth to eleventh embodiments, [45] The solvent is perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluoromethylcyclohexane, perfluorotripropylamine, perfluorotributylamine, perfluorotriamylamine, perfluoro Lotripentylamine, perfluorotrihexylamine, perfluoro-N-methylmorpholine, perfluoro-N-ethylmorpholine, perfluoro-N-isopropylmorpholine, perfluoro-N-methylpyrroli Dean, perfluoro-1,2-bis(trifluoromethyl)hexafluorocyclobutane, perfluoro-2-butyltetrahydrofuran, perfluorotridetylamine, perfluorodibutylether, or two of them It relates to a method of manufacturing a lithium metal secondary battery including the above. [46] In the thirteenth embodiment of the present invention, in any one of the 9th to 12th embodiments, [47] The content of the release agent is 0.1 to 80% by weight based on the total weight of the release solution, relates to a method of manufacturing a lithium metal secondary battery. Effects of the Invention [48] The case for a lithium metal secondary battery according to the present invention includes a releasable capsule on the inner surface of the exterior material, so that when a through member inserted from the outside penetrates the inside of the electrode assembly, the releasability of the lithium metal negative electrode to the through member may be improved. [49] In addition, as the releasability of the lithium metal to the penetrating member is increased by the releasable capsule, it is possible to provide a more improved lithium metal secondary battery in the nail safety test. [50] The present invention can also provide a lithium metal secondary battery having high thermal safety by including a release agent in the releasable capsule. [51] The case for a lithium metal secondary battery according to the present invention may prevent a short circuit of the lithium metal secondary battery by including a releasable capsule. [52] Since the lithium metal secondary battery according to the present invention uses lithium metal as a negative electrode active material, it can provide a high energy density. Moreover, the loss of lithium metal attached to the nail when testing nail safety is small, so It can have a superior energy density compared to. [53] The lithium metal secondary battery according to the present invention may provide a lithium metal secondary battery that does not affect cell performance by including a releasable capsule on the inner surface of the exterior material. Brief description of the drawing [54] 1 is a schematic diagram schematically showing a cross section of a lithium metal secondary battery according to a comparative example of the present invention. [55] 2 is a schematic diagram schematically showing a cross-section of a battery after a nail safety test is performed on a lithium metal secondary battery in a comparative example of the present invention. [56] 3 is a schematic diagram showing a cross-section of a lithium metal secondary battery according to an embodiment of the present invention. [57] 4 is a schematic diagram schematically showing a cross-section of a battery after a nail safety test is performed on a lithium metal secondary battery according to an embodiment of the present invention. [58] 5 is a schematic view schematically showing a releasable capsule according to the present invention. Mode for carrying out the invention [59] Hereinafter, the present invention will be described in detail. The terms or words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is. [60] [61] Hereinafter, the present invention will be described in detail. [62] [63] The present invention relates to a case for a lithium metal secondary battery, a lithium metal secondary battery including the same, and a manufacturing method thereof. [64] [65] A battery using lithium metal as a negative electrode is called a lithium metal secondary battery. This lithium metal secondary battery has an advantage of obtaining a high energy density. However, the lithium metal secondary battery has a problem that nail safety is inferior compared to graphite generally used as a negative electrode active material. This is because lithium metal has soft ductility and has low releasability with respect to the penetrating member penetrating the inside of the electrode assembly. Specifically, in the nail safety test, lithium metal is incorporated into the negative electrode active material layer and/or the electrode assembly while adhering to the surface of the nail penetrating into the electrode assembly. The impregnated lithium metal can contact the positive electrode. Since the lithium metal has high conductivity, a short circuit occurs due to direct contact between the impregnated lithium metal and the positive electrode, leading to ignition. [66] [67] The present invention includes a releasable capsule in order to solve the above problems. [68] Specifically, in the present invention, the above problem is solved by covering the inner surface of the case for a lithium metal secondary battery with a releasable capsule. Accordingly, according to the present invention, when the through member is inserted from the outside into the negative electrode active material layer and/or the electrode assembly in the lithium metal secondary battery, low releasability of the lithium metal negative electrode to the inserted through member can be improved. Accordingly, it is possible to provide a lithium metal secondary battery with improved nail safety. In addition, it is possible to provide a lithium metal secondary battery in which a short circuit is prevented. [69] [70] In the present invention, the releasability refers to the degree to which the lithium metal can be easily peeled from the inserted through member when the through member is inserted into the negative active material layer and/or the electrode assembly from the outside. [71] For example, the lithium metal according to the present invention is a material having low releasability, and is easily adhered to the surface of the penetrating member and does not fall off easily. Therefore, in the case of a lithium metal secondary battery without a releasable capsule, the lithium metal penetrates the inside of the negative electrode active material layer and/or the electrode assembly together with the penetrating member while being attached to the surface of the inserted penetrating member to cause a short circuit. This is schematically shown in FIGS. 1 and 2. 1 and 2 are schematic diagrams schematically showing a nail (through member) before and after penetrating the battery in a lithium metal secondary battery according to a comparative example of the present invention. 1 and 2, in the absence of the releasable capsule, the lithium metal 10 having soft ductility is attached to the surface of the penetrating nail and moves together with the penetrating member 101, so that it is directly connected with the positive electrode 30. Contact with the product may cause a short circuit. [72] On the other hand, the release agent of the present invention is a material having high releasability to the penetrating member, and has a relatively small frictional force with the surface of the penetrating member compared to lithium metal. Accordingly, in the lithium metal secondary battery including the releasable capsule according to the present invention, the lithium metal may be easily peeled off the surface of the inserted through member. That is, the releasability is improved. Accordingly, in the present invention, it is possible to provide a lithium metal secondary battery with improved safety by preventing a short circuit due to contact between the lithium metal and the positive electrode. [73] One aspect of the present invention to solve the above problems, [74] Battery exterior material; It provides a case for a lithium metal secondary battery comprising; one or more releasable capsules attached to at least part or all of the inner surface of the casing to cover the inner surface of the casing and a release solution supported on the releasable capsule. [75] [76] In a specific embodiment of the present invention, [77] The case for a lithium secondary battery includes a releasable capsule attached to a part or all of the inner surface of the battery case. [78] The releasable capsule may be a plurality of capsules. [79] In addition, the releasable film including the releasable capsule may form a layered structure. [80] [81] In a specific embodiment of the present invention, [82] The releasable capsule includes a capsule film and a capsule inner space surrounded by the capsule film, [83] The release solution is supported in the inner space of the capsule, [84] The release solution contains a release agent and a solvent. [85] [86] Hereinafter, the present invention will be described in detail with reference to FIGS. 3 to 5. [87] 3 to 4 are related to a lithium metal secondary battery having a releasable capsule 40, schematically simulating the passage of the penetrating member 101 before and after the battery. In the lithium metal secondary battery having the releasable capsule 40, the releasable capsule is ruptured as the nail is penetrated, and the release solution discharged from the ruptured releasable capsule is attached to the penetrating member 101. Accordingly, since the soft ductile lithium metal is not attached to the penetrating member 101, direct contact between the lithium metal negative electrode and the positive electrode does not occur, so that a short circuit does not occur. [88] 5 schematically simulates the releasable capsule 40, and more specifically, schematically simulates the capsule film 41 and the release solution 42 carried in the capsule surrounded by the capsule film 41. [89] In the present invention, the releasable capsule prevents lithium metal from adhering to the penetrating member when the penetrating member penetrates the negative electrode active material layer and/or the electrode assembly. That is, in a specific embodiment of the present invention, the releasable capsule is not easily attached to the penetrating member inserted from the outside, but is easily peeled off. That is, in the present invention, the releasable capsule acts as a barrier between the lithium metal and the penetrating member to prevent short circuit due to contact between the lithium metal or the conductor and the positive electrode. In addition, the releasable capsule lowers the friction between the lithium metal and the penetrating member. This prevents lithium metal from adhering to the surface of the penetrating member. That is, by including the releasable capsule, there is a feature of the invention in enhancing releasability with external materials inserted into the lithium metal secondary battery. Accordingly, the peeling force or adhesive force between the lithium metal and the penetrating member decreases. [90] In the present invention, by providing the releasable capsule, it is possible to prevent lithium metal from being inserted into the battery together with the penetrating member inserted into the battery. Therefore, short circuit is prevented and the possibility of ignition can be reduced. [91] [92] In the present invention, the releasable film is attached to at least a part or all of the inner surface of the battery casing to cover the inner surface of the casing. [93] In a specific embodiment of the present invention, the releasable film may include one or more releasable capsules carrying a release solution. [94] In the present invention, the releasable capsule is located on the inner surface of the battery case. That is, the battery performance may not be affected by not making direct contact with the electrode assembly including the lithium metal negative electrode. [95] [96] In a specific embodiment of the present invention, the releasable capsule includes a capsule film and a capsule inner space surrounded by the capsule film. [97] The inside of the capsule specifically includes a release solution in the inner space of the capsule surrounded by the capsule film. When the capsule film is ruptured by a penetrating member inserted from the outside, the release agent carried in the capsule is released. [98] In a specific embodiment of the present invention, the releasable coating may include one or more releasable capsules. The releasable capsule may be attached to the inside (inner surface) of the battery case. [99] In a specific embodiment of the present invention, the size of the releasable capsule may be 0.1 to 100 μm. [100] In a specific embodiment of the present invention, the releasable capsule may be in any one of a foam type, a carrier type, and a pocket type. The releasable capsule may be absorbed or supported in a foam type, a matrix type, or a pocket type. The matrix type may be a form in which a release solution is impregnated with a porous support. [101] In the present invention, the method of manufacturing a releasable capsule is not particularly limited as long as it is a technology for manufacturing a capsule carrying a release agent as in the present invention. In a specific embodiment of the present invention, a release agent may be dispersed in an organic solution through an emulsification process, and a polymer may be polymerized on an oily surface thereof to prepare a capsule film. Interfacial polymerization, in-situ polymerization, coacervation, and the like may be used as the polymerization method at this time. [102] The capsule film is ruptured by a penetrating member inserted from the outside. When the capsule film is ruptured, the release agent and the solvent carried in the capsule may be released. [103] In a specific embodiment of the present invention, the capsule film may be ruptured at a pressure of 25 psi or more. The pressure can be measured using a pressure-sensitive paper (Fuji Image Tech Co., Ltd.). [104] [105] The specific conditions under which the releasable film is ruptured may be controlled by physical properties or molecular size of the material itself, and in some cases, may be adjusted by a manufacturing method. [106] In a specific embodiment of the present invention, the capsule coating may include a polymer resin as a capsule coating component. [107] In a specific embodiment of the present invention, the polymer resin is polyolefin, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene Oxide, polyphenylene sulfide, or polyethylene naphthalene, or a mixture of two or more thereof. [108] In a specific embodiment of the present invention, the thickness of the capsule coating may vary depending on the capsule coating component. [109] The releasable capsule contains a release solution carried in the capsule. [110] The release solution contains a release agent and a solvent. [111] The release agent is released from the inside of the capsule when the capsule film is ruptured while the penetrating member penetrates the inside of the negative active material layer and/or the electrode assembly including the same. The released release agent is attached to the surface of the penetrating member to help prevent lithium metal in the lithium metal negative electrode from attaching to the penetrating member. [112] In a specific embodiment of the present invention, the release agent is coated on a negative electrode active material layer and/or a penetrating member penetrating the inside of an electrode assembly including the same to prevent short circuit and delay the ignition temperature, It can be used without. [113] For example, the release agent is vinyl acetate resin, vinyl chloride resin, urethane resin, chlorinated rubber resin, phthalic acid resin, alkyd resin, epoxy resin, phenol resin, melanin resin, acrylic resin, fluorine-based compound fluorine resin, silicone resin, metal It may be any one selected from the group consisting of acrylate resins and rosin, or a mixture of two or more of them. [114] In a specific embodiment of the present invention, the release agent is a vinyl acetate resin, a vinyl chloride resin, a urethane resin, a chlorinated rubber resin, a phthalic acid resin, an alkyd resin, an epoxy resin, a phenol resin, a melanin resin, Acrylic resin, fluorine resin, silicone resin, metal acrylate resin, rosin resin, or two or more of these may be included. [115] Commercially available fluorine-based resin release agents that can be used in the present invention include Daikin's OPTOOL DSX, OPTOOL AES; Shin-Etsu Corporation KY130, KY108; Fluoro Surf FG-5020 from Fluoro Technologies; Dow's Dow 2634. Specifically, as the fluorine-based resin release agent, OPTOOL DSX, which is excellent in releasability and surface lubricity, may be used. The OPTOOL DSX contains a strong bond of carbon (C) and fluorine (F) in its molecular structure, so it is not only stable, but also has excellent effects in non-adhesion, low friction, and durability because it does not want to bond with other materials. [116] Since the fluorine-based resin itself exhibits flame retardancy and thus has high thermal stability, the ignition temperature may be further delayed. [117] [118] The solvent may be dispersed or dissolved in a release agent, and may be used without limitation as long as it does not affect the performance of the electrode assembly. [119] In a specific embodiment of the present invention, the solvent may be an organic solvent. [120] In a specific embodiment of the present invention, the organic solvent is 1-methyl-2-pyrrolidone, dimethylacetamide, acetonitrile, dimethyl sulfoxide ( dimethylsulfoxide) or two or more of them. [121] In a specific embodiment of the present invention, the solvent may be a fluorocarbon-based liquid. [122] The fluorocarbon-based liquid is a hydrocarbon compound in which at least one hydrogen is substituted with fluorine, and is not particularly limited, but specifically perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluoromethylcyclo Hexane, perfluorotripropylamine, perfluorotributylamine, perfluorotriamylamine, perfluorotripentylamine, perfluorotrihexylamine, perfluoro-N-methylpyrrolidine, perfluoro-1,2 -Bis(trifluoromethyl)hexafluorocyclobutane, perfluoro-2-butyltetrahydrofuran, perfluorotridetylamine, perfluorodibutylether, or two or more of these may be included. [123] [124] In a specific embodiment of the present invention, the content of the release agent may be 0.1 to 80% by weight based on the total weight of the release solution. [125] Within the numerical range, it may be 80% by weight or less, or 55% by weight or less, or 50% by weight or less. , Or 20 to 30% by weight. [126] Since the viscosity of the release agent is not too high in the numerical range of the content of the release agent, it can be easily attached to the penetrating member, and the effect of preventing short circuit and delaying ignition is excellent. [127] [128] In the present invention, the penetrating member means a needle-shaped or rod-shaped object that can penetrate into the negative electrode active material layer and/or the electrode assembly. [129] In a specific embodiment of the present invention, the penetrating member is, for example, a conductor or a non-conductor. [130] In a specific embodiment of the present invention, the shape and material of the penetrating member are not particularly limited. However, in the case of a conductor, the conductor penetrating member is inserted into the negative electrode active material layer and/or the electrode assembly and contacts both electrodes to cause a short circuit as current is passed. In addition, in the case of a nonconductor, the lithium metal of the negative electrode in the lithium metal secondary battery is attached to the surface of the inserted nonconductor, so that current can be passed between both electrodes by the nonconductor penetrating member to which the lithium metal is attached. [131] [132] The battery packaging material may be appropriately selected depending on the shape of the electrode assembly and the intended use of the battery. [133] In a specific embodiment of the present invention, when the exterior material is a pouch type, an aluminum laminated pouch including an aluminum layer may be used, and after injecting the electrolyte, the opened portion of the aluminum laminated pouch is thermally welded or heated. It can be sealed by fusion bonding. [134] [135] In addition, the present invention provides a lithium metal secondary battery including the case for a lithium metal battery described above. [136] [137] In a specific embodiment of the present invention, the lithium metal secondary battery, [138] Battery case; And [139] Includes; an electrode assembly charged to the battery case, [140] The electrode assembly includes a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode, and the negative electrode includes lithium metal as a negative electrode active material, [141] The battery case is the case for a lithium metal secondary battery described above. [142] In a specific embodiment of the present invention, the negative electrode may include a negative electrode current collector and a negative active material layer formed on the surface of the negative electrode current collector. [143] In a specific embodiment of the present invention, the negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, Surface treatment of copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadium alloy, and the like may be used. In addition, various forms such as a film, sheet, foil, net, porous material, foam, non-woven fabric, etc. may be used as the form of a film, sheet, foil, net, porous material, foam, non-woven fabric, etc. with or without microscopic requests formed on the surface. [144] In a specific embodiment of the present invention, the negative active material layer may include at least one of a metal thin film, a metal alloy, and a metal powder. [145] In a specific embodiment of the present invention, the negative active material includes lithium metal, and additionally, a lithium alloy, a lithium metal composite oxide, a lithium-containing titanium composite oxide (LTO), graphite, soft carbon, hard carbon ( hard carbon) and any one selected from the group consisting of a combination thereof, or two or more of them. In this case, the lithium alloy includes an element capable of alloying with lithium, and the elements capable of alloying with lithium include Si, Sn, C, Pt, Ir, Ni, Cu, Ti, Na, K, Rb, Cs , Fr, Be, Mg, Ca, Sr, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, or alloys thereof. [146] The negative active material layer may have a thickness of 5 μm to 40 μm. In a specific embodiment of the present invention, the lower limit of the thickness of the negative active material layer may be 5 µm, 7 µm, or 10 µm or more, and the upper limit of the thickness of the negative active material layer may be 40 µm, 30 µm, or 20 µm or less, and these It may be a combination of each of the upper and lower limits. Within the above numerical range, lithium ions may sufficiently diffuse into the interior of the negative active material layer. In addition, the negative electrode active material layer may be supported by the negative electrode current collector within the numerical range, and there is little problem of reducing the energy density per negative electrode volume. [147] In a specific embodiment of the present invention, the negative active material layer may be prepared by coating, bonding, rolling, or depositing a metal foil on a flat negative current collector. Alternatively, it may be prepared by applying metal powder on the current collector. Meanwhile, the negative active material layer may be formed of only a metal thin film or a metal alloy without a current collector. In a specific embodiment of the present invention, the negative active material layer may be prepared by physically bonding or rolling a lithium metal to a current collector. In a specific embodiment of the present invention, the negative active material layer may be prepared by electro-depositing lithium metal or chemical vapor deposition on a current collector. [148] [149] In a specific embodiment of the present invention, the positive electrode is not particularly limited, and the positive electrode active material may be prepared in a state bound to the positive electrode current collector according to a conventional method known in the art. As a non-limiting example of the positive electrode active material, a conventional positive electrode active material that can be used for the positive electrode of a conventional electrochemical device may be used, and in particular, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a combination of these lithium composites It is preferred to use an oxide. [150] The separator that can be used in the lithium metal secondary battery of the present invention may be used without limitation as long as it is an insulating film that electrically insulates the negative electrode and the positive electrode. In a specific embodiment of the present invention, the separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength may be used. The pore diameter of the separator is generally 0.01 μm to 10 μm, and the thickness is generally 5 μm to 300 μm. As such a separator, a sheet or nonwoven fabric made of, for example, an olefin-based polymer such as polyethylene or polypropylene having chemical resistance and hydrophobicity, glass fiber or polyethylene may be used. [151] In a specific embodiment of the present invention, the separator may be formed with a porous coating layer in which inorganic particles are bound by an organic binder polymer on at least one surface of a porous polymer substrate. The separator may increase heat resistance stability by including a porous coating layer. [152] In a specific embodiment of the present invention, the porous polymer substrate can be used as long as it is a planar porous polymer substrate used for an electrochemical device, for example, has high ion permeability and mechanical strength, and has a pore diameter of generally 0.01 μm. A thin insulating film having a thickness of ~ 10 µm and a thickness of 5 µm to 300 µm may be used. For example, a porous polymer film made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer can be used alone or by laminating them. Or, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used, but is not limited thereto. [153] In a specific embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. [154] That is, the inorganic particles that can be used in the present invention are not particularly limited as long as the oxidation and/or reduction reaction does not occur in the operating voltage range of the applied electrochemical device (eg, 0 to 5V based on Li/Li + ). Particularly, when inorganic particles having a high dielectric constant are used as inorganic particles, the ionic conductivity of the electrolyte may be improved by contributing to an increase in the degree of dissociation of an electrolyte salt, such as a lithium salt, in a liquid electrolyte. [155] For the reasons described above, the inorganic particles preferably include high-k inorganic particles having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO 3 , Pb(Zr,Ti)O 3 (PZT), Pb 1 - x La x Zr 1 -y Ti y O 3 (PLZT, 0