Lithium metal battery and method for manufacturing the same

Abstract

Disclosed are a lithium metal battery and a method of manufacturing the same, the lithium metal battery comprising a positive electrode, a negative electrode current collector, and a gel-type polymer electrolyte disposed between the positive electrode and the negative electrode current collector wherein the gel-type polymer electrolyte comprises a cross-linked polymer and a liquid electrolyte comprising an organic solvent and a lithium salt, and the cross-linked polymer is a product of a reaction between a multifunctional cross-linking agent having three or more functional groups and a (meth) acrylate-based compound having a polyethylene glycol moiety.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a lithium metal battery and a method of manufacturing the same. BACKGROUND

[0002] Currently available lithium metal batteries mainly use carbon-based negative active materials such as graphite. The carbon-based negative active material does not exhibit volume change during charging and discharging, thereby enhancing the stability of the lithium metal battery; however, a negative active material having a higher capacity is required due to its low capacity.

[0003] Lithium metal having a much larger theoretical capacity than carbon-based negative active materials can be used as a negative active material.

[0004] During charging and discharging, side reactions between lithium metal and an electrolyte cause dendrites to be formed on the surface of the lithium metal, and the growth of the dendrites can cause a short circuit between the positive electrode and the negative electrode, thereby potentially degrading the life characteristics of the lithium metal battery including the lithium metal. SUMMARY

[0005] TECHNICAL PROBLEM An aspect is to provide a lithium metal battery having a novel structure.

[0006] Another aspect is to provide a method of manufacturing the above-described lithium metal battery.

[0007] TECHNICAL SOLUTION According to an embodiment, a lithium metal battery is provided, the lithium metal battery including: a positive electrode; a negative current collector; and an electrolyte layer disposed between the positive electrode and the negative current collector, wherein the electrolyte layer includes a gel-type polymer electrolyte, wherein the gel-type polymer electrolyte includes a liquid electrolyte including an organic solvent and a lithium salt and a cross-linked polymer, wherein the cross-linked polymer includes a reaction product of a multi-functional cross-linking agent having three or more functional groups and a (meth)acrylate compound having a polyethylene glycol moiety.

[0008] The electrolyte layer can further include a separator.

[0009] A negative active material layer, a protective layer, or a combination thereof can be included between the electrolyte layer and the negative current collector.

[0010] A lithium metal layer is further included between the electrolyte layer and the negative current collector, and in XPS analysis of a surface of the lithium metal layer, the intensity of a fluorine peak can be greater than the intensity of an oxygen peak.

[0011] The mixed weight ratio of the multi-functional cross-linking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety is 9:1 to 2:1.

[0012] The gel-type polymer electrolyte includes 90 to 99 parts by weight of a liquid electrolyte and 1 to 10 parts by weight of a cross-linking polymer.

[0013] In the gel-type polymer electrolyte, the content of the liquid electrolyte is, for example, 92 to 99 parts by weight, 94 to 99 parts by weight, or 95 to 97 parts by weight, and the content of the cross-linked polymer is 1 to 8 parts by weight, 1 to 6 parts by weight, for example, 3 to 5 parts by weight.

[0014] The separator includes a porous substrate, and the porous substrate includes polypropylene, polyethylene, or a combination thereof.

[0015] According to another aspect, a method for preparing a lithium metal battery is provided, the method comprising the following steps: preparing a negative electrode current collector; preparing an electrolyte layer; preparing a positive electrode; laminating the negative electrode current collector, the electrolyte layer and the positive electrode to prepare an assembly; injecting a composition for forming a gel-type polymer electrolyte into the assembly, wherein the composition comprises a multifunctional cross-linking agent having three or more functional groups, a (meth)acrylate compound having a polyethylene glycol portion and a liquid electrolyte comprising an organic solvent and a lithium salt; and cross-linking the injected composition for forming a gel-type polymer electrolyte to prepare a lithium metal battery comprising a gel-type polymer electrolyte.

[0016] A negative electrode active material layer is further laminated on the negative electrode current collector and crosslinked by heat treatment at 40°C to 120°C.

[0017] The composition for forming a gel-type polymer electrolyte includes a multifunctional cross-linking agent having three or more functional groups, a (meth)acrylate compound having a polyethylene glycol moiety, a lithium salt, an organic solvent, and an initiator.

[0018] Beneficial effects According to an aspect, a gel-type polymer electrolyte having improved ionic conductivity and enhanced oxidation stability is provided. By using such a gel-type polymer electrolyte, a lithium metal battery having improved high-rate characteristics and lifespan characteristics is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The stack structure of a lithium metal battery according to an embodiment is schematically shown.

[0020] Figure 2 FIG. 1 schematically shows a stacked structure of a lithium metal battery according to another embodiment.

[0021] Figure 3 is a schematic diagram of a lithium metal battery according to an embodiment.

[0022] Figure 4is a schematic view of a lithium metal battery according to another embodiment.

[0023] Figure 5 is a schematic view of a lithium metal battery according to another embodiment.

[0024] <Description of Major Reference Numerals in the Drawings> DETAILED DESCRIPTION

[0025] The inventive concept described below can be subject to various modifications and can have various embodiments, and specific embodiments are shown and described in detail in the drawings and the detailed description. However, this is not intended to limit the inventive concept to the specific embodiments, but it should be understood to include all modifications, equivalents, or alternatives falling within the technical scope of the inventive concept.

[0026] The terms used below are merely used to describe specific embodiments, and are not intended to limit the inventive concept. Unless the context clearly indicates otherwise, a singular expression includes a plural expression. In the following, the term "comprising" or "having" and the like will be understood to indicate that there is the feature, numeral, process, operation, element, component, ingredient, material, or combination described in the specification, and will not be interpreted as excluding the possibility of existence or addition of one or more other features, numerals, processes, operations, elements, components, ingredients, materials, or combinations. The symbol " / " used herein can be interpreted as "and" or "or" according to the context.

[0027] In the drawings, the thickness of each layer and region can be exaggerated or reduced for the sake of clarity. Throughout the specification, like reference numerals refer to like elements. Throughout the specification, when a portion such as a layer, a film, a region, or a plate is described as "on" or "above" another portion, the portion not only includes a case where it is directly on the other portion, but also includes a case where another portion is interposed therebetween. Throughout the specification, terms such as "first" and "second" can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only to distinguish one element from another element. In the present specification and drawings, for components having substantially the same function and structure, the same reference numerals are used and redundant descriptions are omitted.

[0028] As used herein, the term "particle size" of a particle refers to the average diameter in the case of spherical particles and the average longest axial length in the case of non-spherical particles. Particle size can be measured using a particle size analyzer (PSA). The "particle size" of a particle is, for example, the average particle size. The average particle size is, for example, the median particle size (D50). The median particle size (D50) is the particle size corresponding to 50% cumulative volume, calculated from the side of the particle size distribution with smaller particle sizes, for example, when measured by a laser diffraction method. When measuring particle size using a scanning electron microscope, the particle size is determined as the average of 30 or more randomly selected particles of 1 pm or more, excluding fine particles.

[0029] As used herein, the term "metal" includes metals and metalloids, such as silicon and germanium, in elemental or ionic states.

[0030] As used herein, the term "alloy" refers to a mixture of two or more metals.

[0031] As used herein, the term "positive active material" refers to a positive material capable of lithiation and delithiation, and the term "negative active material" refers to a negative material capable of lithiation and delithiation.

[0032] As used herein, the terms "lithiation" and "lithiate" refer to a process of adding lithium to a positive active material or a negative active material, and the terms "delithiation" and "delithiate" refer to a process of removing lithium from a positive active material or a negative active material.

[0033] As used herein, the terms "charge" and "charge up" refer to a process of supplying electrochemical energy to a battery, and the terms "discharge" and "discharge from" refer to a process of removing electrochemical energy from a battery.

[0034] As used herein, the terms "positive electrode" and "positive" refer to an electrode that undergoes electrochemical reduction and lithiation during discharge, and the terms "negative electrode" and "negative" refer to an electrode that undergoes electrochemical oxidation and delithiation during discharge.

[0035] Hereinafter, a lithium metal battery according to an embodiment and a method of preparing the same will be described in more detail.

[0036] A negative electrode-free lithium metal battery is a battery that uses only a negative current collector without a negative active material layer. During charging, lithium ions delivered from the positive electrode are plated on the surface of the negative current collector, and during discharging, lithium plated on the negative current collector is peeled off again and inserted into the positive electrode, thereby operating the battery.

[0037] Since the negative-electrode-free lithium metal battery omits lithium metal that is additionally used as a negative active material, it has an advantage of maximizing the unit volume energy density and the unit weight energy density of the battery. However, plated lithium metal can grow into lithium dendrites due to non-uniform current density during the oxidation / reduction process during operation, and the lithium dendrites can cause loss of the lithium negative electrode, thereby deteriorating the capacity and life characteristics of the battery, and can also cause a short circuit between the negative electrode and the positive electrode, thereby causing a safety problem.

[0038] To solve the above problem, the following methods have been proposed: introducing a protective layer to minimize contact between lithium and electrolyte to reduce side reactions, or introducing a liquid electrolyte into a crosslinked polymer network to minimize exposure of the electrolyte on the electrode surface and form a uniform lithium ion flow throughout the electrode, thereby suppressing the growth of lithium dendrites by using a gel-type polymer electrolyte.

[0039] The gel-type polymer electrolytes known so far have a semi-solid form and exhibit improved safety compared to pure liquid electrolytes, but have high resistance and tend to decompose at high voltage, making them difficult to use at high voltage. In addition, conventional gel-type polymer electrolytes mainly use non-ionic conductive crosslinking agents, thus having insufficient ionic conductivity, which needs to be improved.

[0040] The lithium metal battery according to the embodiments includes: a positive electrode; a negative current collector; and an electrolyte layer disposed between the positive electrode and the negative current collector, wherein the electrolyte layer includes a gel-type polymer electrolyte, and the gel-type polymer electrolyte includes a liquid electrolyte containing an organic solvent and a lithium salt and a crosslinked polymer, and the crosslinked polymer includes a reaction product of a multi-functional crosslinking agent having three or more functional groups and a (meth)acrylate compound having a polyethylene glycol moiety. As used herein, the reaction product of the multi-functional crosslinking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety refers to a crosslinking product of the multi-functional crosslinking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety.

[0041] A negative active material layer, a protective layer, or a combination thereof can be included between the negative current collector and the electrolyte layer.

[0042] A separator can also be included between the negative current collector and the electrolyte layer.

[0043] The separator includes a porous substrate. When the lithium metal battery contains a separator, the negative active material layer, the protective layer, or a combination thereof can be disposed between the negative current collector and the separator. As such, the lithium metal battery can include the negative active material layer and / or the protective layer disposed between the negative current collector and the separator, or can be free of the negative active material layer or the protective layer.

[0044] According to an embodiment, a lithium metal battery includes: a negative current collector; an electrolyte layer (separator) disposed on the negative current collector; a gel-type polymer electrolyte disposed on the electrolyte layer (separator); and a positive electrode disposed on the gel-type polymer electrolyte, wherein the gel-type polymer electrolyte includes a liquid electrolyte including an organic solvent and a lithium salt and a cross-linked polymer, and the cross-linked polymer can include a reaction product of a multi-functional cross-linking agent having three or more functional groups and a (meth)acrylate compound having a polyethylene glycol moiety.

[0045] The gel-type polymer electrolyte can be present in pores of the separator or inside the separator.

[0046] The multi-functional cross-linking agent having three or more functional groups refers to a multi-functional cross-linking agent having three or more cross-linkable functional groups. A material that is electrochemically stable under driving conditions of a positive electrode using a positive electrode active material including 90 mol% or more of nickel, for example, at a voltage of about 4.3 V or more, is used. The number of cross-linkable functional groups is, for example, 3 to 10, or 3 to 6. Examples of such a multi-functional cross-linking agent include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane ethoxylated triacrylate, trimethylolpropane propoxylated triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylated tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate (DPHA), tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA), propoxylated glycerol triacrylate, or a combination thereof.

[0047] The (meth)acrylate compound having a polyethylene glycol moiety is a compound that reacts with the multi-functional cross-linking agent having three or more functional groups, and has two or more functional groups capable of participating in a cross-linking reaction. When a cross-linking reaction is performed using such a compound, the degree of cross-linking increases, decomposition at a high voltage is inhibited, oxidation stability is improved, and a gel-type polymer electrolyte having improved ionic conductivity at a high voltage can be obtained.

[0048] The (meth)acrylate compound with a polyethylene glycol moiety contains an ethylene glycol moiety that imparts ionic conductivity, and thus a gel-type polymer electrolyte formed therefrom can exhibit improved ionic conductivity. Examples of the (meth)acrylate compound with a polyethylene glycol moiety include polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, triethylene glycol diacrylate (TEGDA), triethylene glycol dimethacrylate (TEGDMA), tetraethylene glycol diacrylate (TTEGDA), glycidyl methacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), trimethylolpropane trimethacrylate (TMPTMA), or a combination thereof.

[0049] The mixed weight ratio of the multifunctional crosslinking agent having three or more functional groups to the (meth)acrylate compound with a polyethylene glycol moiety is 9:1 to 2:1, 9:1 to 2.5:1, 9:1 to 2.3:1, 9:1 to 3:1, or 6:1 to 4:1. When the mixed weight ratio is within the above range, a gel-type polymer electrolyte having increased crosslinking degree, improved oxidation stability, and enhanced ionic conductivity can be obtained.

[0050] In the gel-type polymer electrolyte, the content of the liquid electrolyte is 90 to 99 parts by weight, 92 to 98 parts by weight, 93 to 97 parts by weight, or for example, 95 to 97 parts by weight, and the content of the crosslinked polymer is 1 to 10 parts by weight, 1 to 8 parts by weight, 2 to 7 parts by weight, or for example, 3 to 5 parts by weight. When the contents of the liquid electrolyte and the crosslinked polymer in the gel-type polymer electrolyte are within the above ranges, the ionic conductivity is improved.

[0051] The ionic conductivity of the gel-type polymer electrolyte is 0.19 S / cm or more or 0.19 S / cm to 0.5 S / cm. A lithium metal battery including the gel-type polymer electrolyte having such ionic conductivity can exhibit improved high-rate characteristics and power output characteristics.

[0052] The gel-type polymer electrolyte containing the liquid electrolyte and the crosslinked polymer is contained in pores of a porous substrate constituting a separator. In the separator having such a structure, the liquid electrolyte is held within a crosslinked polymer network having a crosslinked structure, and is prevented from leaking.

[0053] Reference Figure 1The electrolyte layer 30 and the positive electrode 10 are laminated on the negative electrode current collector 21. The negative electrode 20 includes the negative electrode current collector 21, and there is no negative electrode active material layer. The electrolyte layer 30 can include a separator.

[0054] The positive electrode 10 includes a positive electrode active material layer 12 and a positive electrode current collector 11.

[0055] The electrolyte layer 30 can include a gel-type polymer electrolyte.

[0056] When the electrolyte layer includes a separator, the gel-type polymer electrolyte can be configured to be disposed between the separator and the positive electrode. According to another embodiment, the gel-type polymer electrolyte can not exist between the separator and the positive electrode, and the gel-type polymer electrolyte can exist only inside the separator. Here, the inside of the separator can refer to a hole. According to another embodiment, the gel-type polymer electrolyte can exist on at least one surface of the separator, for example, on both surfaces of the separator. Optionally, the gel-type polymer electrolyte can exist between the negative electrode current collector and the separator. When a negative electrode active material layer, such as a lithium metal layer, exists on the negative electrode current collector, the gel-type polymer electrolyte can also exist between the negative electrode active material layer and the separator.

[0057] The separator can include a porous substrate. The pores of the separator can contain a gel-type polymer electrolyte including a liquid electrolyte and a cross-linked polymer.

[0058] The pore diameter of the separator is substantially 0.01 µm to 10 µm, and the thickness is 5 µm to 20 µm. As such a separator, for example, an olefin-based polymer such as polypropylene; or a sheet or nonwoven fabric made of glass fiber or polyethylene is used. When a solid polymer electrolyte is used as an electrolyte, the solid polymer electrolyte can also be used as a separator.

[0059] Among the separators, specific examples of the olefin-based polymer include polyethylene, polypropylene, or a multilayer film including two or more layers thereof. A hybrid multilayer film such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene triple-layer separator, and a polypropylene / polyethylene / polypropylene triple-layer separator can be used.

[0060] In the lithium metal battery according to the embodiment, the liquid electrolyte is absorbed into the polymer matrix of the gel-type polymer electrolyte, so that no leakage occurs. Electrochemical side reactions and electrolyte decomposition reactions occurring at the positive electrode and the negative electrode are inhibited, thereby ensuring stability and improving battery performance.

[0061] The gel-type polymer electrolyte contains a liquid electrolyte, and the liquid electrolyte includes a lithium salt and an organic solvent.

[0062] The lithium salt includes a first lithium salt and a second lithium salt. By including the first lithium salt and the second lithium salt in the gel-type polymer electrolyte, the ionic conductivity of the gel-type polymer electrolyte can be improved.

[0063] The first lithium salt and the second lithium salt are borate-based lithium salts. The borate-based lithium salt has better high-temperature stability than a phosphorus-based lithium salt, and can suppress the generation of hydrofluoric acid (HF). By including the borate-based lithium salt as the first lithium salt and the second lithium salt, the high-temperature cycle characteristics of the lithium metal battery can be improved.

[0064] The first lithium salt and the second lithium salt may, for example, independently be fluorine-containing borate-based lithium salts. By including the fluorine-containing borate-based lithium salt as the first lithium salt and the second lithium salt, the composition of the SEI layer formed during charging and discharging of the lithium metal battery can be more effectively changed. For example, as the fluorine (F) content in the SEI layer increases, the structural stability of the SEI layer increases, and side reactions with organic solvents can be effectively suppressed. As a result, the reversibility of the electrode reaction of the lithium metal battery can be improved.

[0065] The first lithium salt and the second lithium salt may, for example, respectively be a non-cyclic lithium borate salt and a cyclic lithium borate salt. By including the non-cyclic lithium borate salt as the first lithium salt, the ionic conductivity of the gel-type polymer electrolyte can be more effectively increased. By including the cyclic lithium borate salt as the second lithium salt, the aggregation of anions can increase, which can more effectively contribute to the change in SEI layer composition and improve the high-temperature stability of the gel-type polymer electrolyte.

[0066] By not including the first lithium salt, the ionic conductivity of the gel-type polymer electrolyte can decrease. By not including the second lithium salt, the structural stability of the SEI layer can decrease.

[0067] The fluorine-containing borate-based lithium salt may, for example, include LiBF4, LiBF3(C2F5), a compound represented by any one of Formulae 1 to 12, or a combination thereof.

[0068] <Formula 1> <Formula 2>

[0069] <Formula 3> <Formula 4>

[0070] <Formula 5> <Formula 6>

[0071] <Formula 7> <Formula 8>

[0072] <Formula 9> <Formula 10>

[0073] <Formula 11> <Formula 12>

[0074] The first lithium salt can include, for example, LiBF4, and the second lithium salt can include a compound selected from the compounds represented by Formulas 1 to 12.

[0075] The first lithium salt can include LiBF4, and the second lithium salt can include, for example, a compound of Formula 1.

[0076] The gel-type polymer electrolyte can, for example, not include a phosphorus-based lithium salt. By not including a phosphorus-based lithium salt, the gel-type polymer electrolyte can exhibit improved high-temperature stability and can inhibit the generation of hydrofluoric acid (HF).

[0077] The gel-type polymer electrolyte can, for example, not include LiBOB. By not including LiBOB, the ionic conductivity of the gel-type polymer electrolyte can be further improved, and the solubility of the lithium salt in the carbonate-based solvent can be enhanced.

[0078] The contents of the first lithium salt and the second lithium salt in the gel-type polymer electrolyte can, for example, independently be greater than 0 and not greater than 1.2 M, 0.1 M to 1.0 M, or 0.4 M to 0.8 M. By having the first lithium salt and the second lithium salt both within these content ranges, the gel-type polymer electrolyte can simultaneously provide excellent ionic conductivity and formation of a structurally stable SEI layer.

[0079] The contents of the first lithium salt and the second lithium salt can, for example, independently be greater than 0 and not greater than 1.2 M, 0.1 M to 1.0 M, or 0.4 M to 0.8 M, with respect to the precursor composition for forming the gel-type polymer electrolyte before adding the first crosslinking monomer and the thermal initiator.

[0080] The content ratio of the first lithium salt to the second lithium salt can be, for example, 1:9 to 9:1, 3:7 to 7:3, or 4:6 to 6:4. By having the first lithium salt and the second lithium salt in these content ratios, the gel-type polymer electrolyte can simultaneously provide excellent ionic conductivity and formation of a structurally stable SEI layer. The content ratio of the first lithium salt to the second lithium salt can be, for example, a molar ratio.

[0081] The gel-type polymer electrolyte includes a first organic solvent and a second organic solvent. By including the first organic solvent and the second organic solvent in the gel-type polymer electrolyte, the interfacial resistance between the gel-type polymer electrolyte and the positive electrode and / or the interfacial resistance between the gel-type polymer electrolyte and the plated lithium metal layer during charging can be more effectively reduced. The first organic solvent and the second organic solvent include, for example, a carbonate-based compound. The first organic solvent and the second organic solvent are, for example, carbonate-based organic solvents. By including the first organic solvent and the second organic solvent of the carbonate-based in the gel-type polymer electrolyte, the first lithium salt and the second lithium salt can be easily dissolved in the organic solvent, and the viscosity of the precursor composition for forming the gel-type polymer electrolyte can be reduced. The first organic solvent includes, for example, a chain carbonate compound. By using a chain carbonate-based solvent as the first organic solvent, the viscosity of the precursor composition before cross-linking can be reduced. The handling of the precursor composition can be easier. The second organic solvent includes, for example, a cyclic carbonate compound substituted with a substituent. The substituent of the cyclic carbonate compound includes, for example, a halogen, a cyano (CN), a nitro group (NO2), or a combination thereof. By using a cyclic carbonate-based solvent substituted with a substituent as the second organic solvent, the first lithium salt and the second lithium salt can be more easily dissolved in the precursor composition for forming the gel-type polymer electrolyte, and the substituent can participate in the formation of the SEI layer, thereby improving the structural stability of the SEI layer. The first organic solvent can include, for example, diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, or a combination thereof. The second organic solvent can include, for example, a vinylene carbonate substituted with one or more substituents selected from a halogen, a cyano (CN), and a nitro group (NO2), a vinyl ethylene carbonate substituted with one or more substituents selected from a halogen, a cyano (CN), and a nitro group (NO2), fluoroethylene carbonate (FEC), a fluoroethylene carbonate substituted with one or more substituents selected from a halogen, a cyano (CN), and a nitro group (NO2), or a combination thereof. The first organic solvent can include, for example, diethyl carbonate, and the second organic solvent can include, for example, a fluorine-substituted cyclic carbonate compound. The second organic solvent can include, for example, fluoroethylene carbonate. The gel-type polymer electrolyte can include, for example, no unsubstituted cyclic carbonate-based solvent. By including no unsubstituted cyclic carbonate-based solvent, the first lithium salt and the second lithium salt can be more easily dissolved in the precursor composition for forming the gel-type polymer electrolyte. The volume ratio of the first organic solvent to the second organic solvent can be, for example, 5.5:4.5 to 9:1, 6:4 to 9:1, 6:4 to 8:2, or 6:4 to 7:3. By having the volume ratio of the first organic solvent to the second organic solvent in such a range, a composition for forming a gel-type polymer electrolyte having excellent lithium salt solubility and low viscosity can be provided.A gel-type polymer electrolyte obtained from a composition for forming a gel-type polymer electrolyte having excellent lithium salt solubility and low viscosity may provide excellent mechanical properties and improved ionic conductivity.

[0082] The lithium salt can be, for example, one or more selected from LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiC(CF3SO2)3, LiC(FSO2)3, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(CF3)3 and LiB(C2O4)2.

[0083] The concentration of the lithium salt in the liquid electrolyte may be, for example, 1 M to 5 M or 1 M to 2.5 M. Within this range, a sufficient amount of lithium ions required for charging and discharging a lithium metal battery may be generated.

[0084] As the organic solvent, for example, an aprotic organic solvent such as N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate and ethyl propionate can be used. Among them, carbonate solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate and diethyl carbonate can be used.

[0085] According to the embodiment, when the gel-type polymer electrolyte exists in the pores of the porous substrate, the interface resistance between the positive electrode, the negative electrode, and the separator may be minimized, and the movement of lithium may be facilitated.

[0086] like Figure 2 As shown in FIG, the negative electrode active material layer 22 may be provided between the negative electrode current collector 21 and the electrolyte layer 30 .

[0087] The negative electrode active material layer 22 may be formed by plating lithium metal during charging. In this way, the negative electrode active material layer 22 may be a plated lithium layer. The plated lithium layer is a lithium metal layer.

[0088] The lithium metal layer serves as, for example, a lithium reservoir. The lithium alloy can include, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., but is not limited thereto, and any alloy known in the related art field to serve as a lithium alloy can be used. The lithium metal layer can be formed of lithium, a combination of one or more of the above-mentioned alloys. The lithium metal layer is, for example, a plated layer. The lithium metal layer can be plated between the electrolyte layer 30 and the negative electrode current collector 21 during charging of the lithium metal battery 1.

[0089] The lithium metal layer is a metal layer including lithium or a lithium alloy. The lithium metal layer includes lithium or a lithium alloy. The lithium metal layer serves as, for example, a lithium reservoir. The lithium alloy can include, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., but is not limited thereto, and any lithium alloy known in the related art field to serve as a lithium alloy can be used. The lithium metal layer can be composed of one of these alloys or lithium, or can be composed of a combination of several types of alloys. The lithium metal layer can be, for example, a plated layer. The lithium metal layer is, for example, plated between the electrolyte layer 30 and the negative electrode current collector 21 during charging of the lithium metal battery 1.

[0090] The thickness of the lithium metal layer is not particularly limited, but is, for example, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, 1 µm to 50 µm, 1 µm to 30 µm, 1 µm to 22 µm, or 1 µm to 10 µm. If the thickness of the lithium metal layer is too thin, it is difficult for the lithium metal layer to function as a lithium reservoir. If the thickness of the lithium metal layer is too thick, the volume of the lithium metal battery 1 can excessively increase, and the cycle characteristics of the lithium metal battery 1 can be deteriorated instead.

[0091] The thickness of the lithium metal layer can be less than the thickness of the positive electrode active material layer 12. For example, the thickness of the lithium metal layer can be 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less of the thickness of the positive electrode active material layer 12. The thickness of the lithium metal layer can be, for example, 1% to 70%, 1% to 60%, 1% to 50%, 1% to 40%, or 1% to 30% of the thickness of the positive electrode active material layer 12. By making the thickness of the lithium metal layer less than the thickness of the positive electrode active material layer, the volume change during charging and discharging of the lithium metal battery 1 can be suppressed. As a result, deterioration due to the volume change of the lithium metal battery 1 can be suppressed.

[0092] The gel-type polymer electrolyte can effectively prevent the deterioration of the lithium metal battery by suppressing side reactions with the lithium metal layer during charging and discharging of the lithium metal battery. For example, during charging and discharging of the lithium metal battery, an SEI (solid electrolyte interface) layer can be formed between the gel-type polymer electrolyte and the plated lithium metal layer. By changing the SEI layer to have an increased content of lithium salt decomposition products, side reactions between the gel-type polymer electrolyte and the lithium metal layer can be more effectively suppressed. Furthermore, the gel-type polymer electrolyte and / or the modified SEI layer can more effectively suppress the growth of lithium dendrites from the lithium metal layer, thereby effectively preventing internal short circuits of the lithium metal battery.

[0093] The separator is disposed on the negative current collector, and further includes a lithium metal layer between the negative current collector and the separator. In X-ray photoelectron spectroscopy (XPS) analysis of a surface of the lithium metal layer, for example, a peak intensity originating from a fluorine (F) element can be greater than a peak intensity originating from an oxygen (O) element. In the XPS analysis of the surface of the lithium metal layer, the peak intensity originating from the fluorine (F) element can be greater than the peak intensity originating from the oxygen (O) element by 100%, 105% or more, 110% or more, or 120% or more. In the XPS analysis of the surface of the lithium metal layer, the peak intensity originating from the fluorine (F) element can be, for example, greater than 100% and up to 200%, 105% to 200%, 110% to 200%, or 120% to 200% of the peak intensity originating from the oxygen (O) element. When the SEI layer formed on the surface of the lithium metal layer mainly includes an inorganic compound containing fluorine (F), the structural stability of the SEI layer can be improved. As a result, the cycle characteristics of the lithium metal battery 1 can be improved. In contrast, when the SEI layer formed on the surface of the lithium metal layer mainly includes an organic compound containing oxygen (O), the structural stability of the SEI layer can be deteriorated. The peak originating from the fluorine (F) element can be, for example, a peak originating from a fluorine (F) 1s orbital. The peak originating from the oxygen (O) element can be, for example, a peak originating from an oxygen (O) 1s orbital.

[0094] After the lithium metal battery 1 is assembled, the lithium metal layer is plated by charging, and since the lithium metal layer is not included when the lithium metal battery 1 is assembled, the energy density of the lithium metal battery 1 is increased. When the lithium metal layer is additionally provided by charging after the lithium metal battery 1 is assembled, the region between the negative electrode 20 (i.e., the negative current collector 21) and the electrolyte layer 30 (e.g., in the initial state or in the fully discharged state of the lithium metal battery 1) is a Li-free region that does not contain lithium (Li).

[0095] Optionally, the negative active material layer 22 can be provided when the lithium metal battery is assembled. The thickness of the negative active material layer is 1 µm to 500 µm, 3 µm to 500 µm, 5 µm to 500 µm, or 10 µm to 500 µm. When the thickness of the negative active material layer is within the above range, a lithium metal battery having improved cycle characteristics can be manufactured without reducing the energy density.

[0096] Instead of the negative active material layer, a protective layer can be formed. The thickness of the protective layer is 1 µm to 20 µm. The protective layer can include, for example, a polymer such as polyvinyl alcohol, polyimide, vinylidene-hexafluoropropylene copolymer, polyvinylidene fluoride, carboxymethyl cellulose, or styrene-butadiene rubber, or a polymer containing an inorganic filler. The inorganic filler can include, for example, SiO2, Al2O3, Al(OH)3, AlO(OH), TiO2, BaTiO3, ZnO2, Mg(OH)2, aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), or a combination thereof. By additionally introducing such a protective layer, contact between lithium and the electrolyte can be minimized to reduce side reactions, and uniform lithium ion flow can be formed throughout the electrode to inhibit the growth of lithium dendrites.

[0097] The negative active material layer 22 includes lithium metal or a lithium alloy. Optionally, when the negative active material layer is provided at the time of battery assembly, the negative active material layer can include only a carbon-based material, or include a combination of a carbon-based material and one or more selected from a metal and a metalloid.

[0098] The carbon-based material includes amorphous carbon, and the average particle diameter of the amorphous carbon is 10 nm to 100 nm. The carbon-based material can include, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, or a combination thereof.

[0099] According to an embodiment, the negative active material layer can include a lithium foil, a lithium powder, or a combination thereof.

[0100] The lithium foil can include, for example, a lithium metal foil, a lithium alloy foil, or a combination thereof. The lithium powder can include a lithium metal powder, a lithium alloy powder, or a combination thereof. The lithium alloy is an alloy of lithium and another metal capable of forming an alloy with lithium, and the lithium alloy contains lithium and a first metal. The first metal can be indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), zinc (Zn), nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0101] The lithium alloy can include, for example, a lithium-silver alloy, a lithium-zinc alloy, a lithium-magnesium alloy, or a lithium-tin alloy. The negative electrode active material layer including a lithium metal foil can be, for example, a lithium metal layer. The negative electrode active material layer including a lithium alloy foil can be, for example, a lithium alloy layer. The negative electrode active material layer including lithium metal powder and / or lithium alloy powder can be introduced by coating a slurry including lithium powder and a binder on a negative electrode current collector. The binder can be, for example, a fluorine-based binder such as polyvinylidene fluoride (PVDF). The negative electrode active material layer can not include a carbon-based negative electrode active material. Accordingly, the negative electrode active material layer can be composed of a metal-based negative electrode active material.

[0102] The negative electrode current collector is composed of a material that does not react with lithium (i.e., a material that neither forms an alloy nor a compound with lithium). The material composing the negative electrode current collector can be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not limited thereto, and any material known in the related art field to be used as an electrode current collector can be used. The negative electrode current collector can be composed of one of the above-described metals, or an alloy or a coated material of two or more metals, for example, the negative electrode current collector can include nickel-plated copper. The negative electrode current collector is, for example, in the form of a plate or a foil.

[0103] The negative electrode active material layer can include a negative electrode active material and a binder.

[0104] The negative electrode active material is, for example, in the form of a particle. The average particle diameter of the negative electrode active material in the form of a particle can be, for example, 10 nm to 4 µm, 10 nm to 3 µm, 10 nm to 2 µm, 10 nm to 1 µm, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 100 nm, or 20 nm to 80 nm. Since the negative electrode active material has an average particle diameter in such a range, reversible plating and / or dissolution of lithium during charging and discharging can be more facilitated. The average particle diameter of the negative electrode active material is, for example, a median particle diameter (D50) measured using a laser particle size distribution analyzer.

[0105] The negative active material can include, for example, at least one selected from a carbon-based negative active material and a metal or metalloid negative active material. The carbon-based negative active material can be, for example, amorphous carbon. The carbon-based negative active material can include, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, or a combination thereof, but is not necessarily limited thereto, and any material classified as amorphous carbon in the related art field can be used. Amorphous carbon refers to carbon that is not crystalline or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon. The metal or metalloid negative active material includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto, and any metal or metalloid negative active material that forms an alloy or a compound with lithium in the related art field can be used. For example, nickel (Ni) is not considered a metal negative active material in the present specification because it does not form an alloy with lithium. The negative active material layer includes one type of negative active material among the above-described negative active materials, or includes a mixture of two or more different negative active materials. The negative active material layer can include, for example, a mixture of amorphous carbon and at least one selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture can be, for example, a weight ratio of 10:1 to 1:2, 10:1 to 1:1, 7:1 to 1:1, 5:1 to 1:1, or 4:1 to 2:1. The negative active material included in the negative active material layer can include, for example, a mixture of first particles composed of amorphous carbon and second particles composed of a metal or a metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The content of the second particles can be 8 wt% to 60 wt%, 10 wt% to 50 wt%, 15 wt% to 50 wt%, 15 wt% to 40 wt%, 20 wt% to 40 wt%, or 20 wt% to 30 wt%, based on the total weight of the mixture. By having the content of the second particles in such a range, for example, the cycle characteristics of the lithium metal battery can be further improved.

[0106] The binder included in the negative active material layer can be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, or the like, but is not necessarily limited thereto, and any binder used in the related art field can be used. The binder can be composed of a single or a plurality of different binders. If the negative active material layer does not include a binder, the negative active material layer can easily be separated from the negative current collector 21. The content of the binder included in the negative active material layer can be, for example, 1 wt% to 20 wt% based on the total weight of the negative active material layer.

[0107] The thickness of the negative active material layer can be, for example, 1 µm to 200 µm, 5 µm to 100 µm, or 10 µm to 50 µm. The thickness of the negative active material layer can be, for example, 1% to 50%, 1% to 30%, 1% to 10%, or 1% to 5% of the thickness of the positive active material layer. If the thickness of the negative active material layer is too thin, lithium dendrites formed between the negative active material layer and the negative current collector can collapse the negative active material layer, and it can be difficult to improve the cycle characteristics of the lithium metal battery. If the thickness of the negative active material layer is excessively increased, the energy density of the lithium metal battery employing the negative electrode 20 can decrease, and it can be difficult to improve the cycle characteristics.

[0108] As the thickness of the negative active material layer decreases, for example, the charge capacity of the negative active material layer also decreases. The charge capacity of the negative active material layer can be, for example, 0.1% to 50%, 1% to 30%, 1% to 10%, 1% to 5%, or 1% to 2%, based on the charge capacity of the positive active material layer. If the charge capacity of the negative active material layer is too small, lithium dendrites formed between the negative active material layer and the negative current collector can collapse the negative active material layer, and it can be difficult to improve the cycle characteristics of the lithium metal battery. If the charge capacity of the negative active material layer is excessively increased, the energy density of the lithium metal battery employing the negative electrode 20 can decrease, and it can be difficult to improve the cycle characteristics. The charge capacity of the positive active material layer is obtained by multiplying the charge capacity density (mAh / g) of the positive active material by the mass of the positive active material in the positive active material layer. In the case of using multiple types of positive active materials, the value of the charge capacity density x mass is calculated for each positive active material, and the sum of these values is taken as the charge capacity of the positive active material layer. The charge capacity of the negative active material layer is also calculated in the same manner. That is, the charge capacity of the negative active material layer is obtained by multiplying the charge capacity density (mAh / g) of the negative active material by the mass of the negative active material in the negative active material layer. In the case of using multiple types of negative active materials, the value of the charge capacity density x mass is calculated for each negative active material, and the sum of these values is taken as the capacity of the negative active material layer. Here, the charge capacity density of the positive material and the negative material is the capacity estimated using a full solid-state half battery using lithium metal as a counter electrode. By measuring the charge capacity using a full solid-state half battery, the charge capacity of the positive active material layer and the negative active material layer is directly measured. By dividing the measured charge capacity by the mass of each active material, the charge capacity density is obtained. Alternatively, the charge capacity of the positive active material layer and the negative active material layer can be the initial charge capacity measured during the first charge cycle.

[0109] [lithium metal battery] The lithium metal battery according to the embodiments includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. Such a lithium metal battery can provide excellent life characteristics. The lithium metal battery can be, for example, a lithium primary battery, a lithium secondary battery, a lithium sulfur battery, or a lithium air battery, but is not limited thereto, and can include any lithium metal battery used in the related art.

[0110] The lithium metal battery can be prepared by the following exemplary methods, although the methods are not necessarily limited thereto, and can be adjusted according to the desired conditions.

[0111] [positive electrode] First, a positive electrode active material composition is prepared by mixing a positive electrode active material, a conductive material, a binder, and a solvent. The prepared positive electrode active material composition is directly coated on an aluminum current collector and dried to manufacture a positive electrode plate having a positive electrode active material layer. Alternatively, the positive electrode active material composition is cast on a separate support, and then a film obtained by peeling from the support is laminated on the aluminum current collector to manufacture a positive electrode plate having a positive electrode active material layer.

[0112] The positive electrode active material is a metal oxide containing lithium, and any material commonly used in the art can be used without limitation. For example, one or more complex oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used. Specific examples include compounds represented by any one of the following chemical formulas: Li a A 1-b B b D2(wherein, 0.90≤a≤1, and 0≤b≤0.5); Li a E 1-b B b O 2-c D c (wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B b O 4-c D c (wherein, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c D α (wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α F α (wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Co b B c O 2-α F2(wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c D α (wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li aNi 1-b-c Mn b B c O 2-α F α (wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α F2(wherein, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2(wherein, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2(wherein, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2(wherein, 0.90≤a≤1, 0.001≤b≤0.1); Li a CoG b O2(wherein, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2(wherein, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4(wherein, 0.90≤a≤1, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); and LiFePO4.

[0113] In the chemical formula representing the above compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating formed on the surface of the above compound can also be used, and a mixture of the above compound and a compound having a coating can also be used. The coating added to the surface of the above compound includes a coating element compound, for example, an oxide of a coating element, a hydroxide of a coating element, a hydroxyl oxide of a coating element, an oxy carbonate of a coating element, or a hydroxyl carbonate of a coating element. The compound forming the coating is amorphous or crystalline. The coating element included in the coating includes Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method of forming the coating is selected within a range that does not adversely affect the properties of the positive electrode active material. The coating method can be, for example, spraying, dipping, or the like. Since the specific coating method is well known to those skilled in the art, a detailed description of the specific coating method is omitted here.

[0114] The positive electrode active material can be, for example: Li a Ni x Co y M z O 2-b A b (wherein, 1.0≤a≤1.2, 0≤b≤0.2, 0.8≤x<1, 0<y≤0.3, 0<z≤0.3, and x+y+z=1; M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof; and A is F, S, Cl, Br, or a combination thereof), LiNi x Co y Mn z O2(wherein, 0.8≤x≤0.95, 0≤y≤0.2, 0<z≤0.2, and x+y+z=1), LiNi x Co y Al z O2(wherein, 0.8≤x≤0.95, 0≤y≤0.2, 0<z≤0.2, and x+y+z=1), LiNi x Co y Mnz Al w O₂ (where 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, 0 < w ≤ 0.2, and x + y + z + w = 1), Li a Co x M y O 2-b A b (where 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1; M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof; and A is F, S, Cl, Br or a combination thereof), Li a Ni x Mn y M' z O 2-b A b (where 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, and x + y + z = 1; M' is cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof; and A is F, S, Cl, Br or a combination thereof), Li a M1 x M2 y PO 4-b X b (where 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, 0 ≤ b ≤ 2; M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof; M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (T), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof; and X is O, F, S, P or a combination thereof), Li a M3 z PO₄ (where 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1; M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof).

[0115] As the conductive material, carbon black, fine graphite particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon nanotubes, metal powders, metal fibers or metal tubes such as copper, nickel, aluminum, and silver, or conductive polymers such as polyaniline derivatives can be used, but are not limited thereto, and any material used as a conductive material in the art can be used. Alternatively, the cathode can not include a separate conductive material.

[0116] As the binder, a vinylidene fluoride / hexafluoropropylene copolymer, a polyvinylidene fluoride, a polyacrylonitrile, a polymethyl methacrylate, a polytetrafluoroethylene (PTFE), a styrene-butadiene rubber-based polymer, or a mixture of the above polymers is used, and as the solvent, N-methyl-2-pyrrolidone (NMP), acetone, or water is used. However, the binder and the solvent are not limited thereto, and any material used in the related art field can be used.

[0117] A pore can also be formed inside the electrode plate by further adding a plasticizer or a pore-forming agent to the cathode active material composition.

[0118] The content of the cathode active material, the conductive material, the binder, and the solvent used in the cathode is at a level commonly used in lithium batteries. One or more of the conductive material, the binder, and the solvent can be omitted depending on the application and the configuration of the lithium metal battery.

[0119] The content of the binder included in the cathode can be 0.1 wt% to 10 wt% or 0.1 wt% to 5 wt% based on the total weight of the cathode active material layer. The content of the cathode active material included in the cathode can be 80 wt% to 99 wt%, 90 wt% to 99 wt%, or 95 wt% to 99 wt% based on the total weight of the cathode active material layer.

[0120] In an embodiment of the disclosure, the cathode current collector 11 can include, for example, a base film and a metal layer disposed on one or both surfaces of the base film.

[0121] The cathode current collector can be a plate or a foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The thickness of the cathode current collector can be, for example, 1 µm to 100 µm, 1 µm to 50 µm, 5 µm to 25 µm, or 10 µm to 20 µm.

[0122] The positive electrode current collector can include, for example, a base film and a metal layer disposed on one or both surfaces of the base film. The base film can include, for example, a polymer. The polymer can be, for example, a thermoplastic polymer. The polymer can include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The base film can be, for example, an insulator. By including an insulating thermoplastic polymer in the base film, the base film can soften or melt when a short circuit occurs, thereby cutting off the operation of the battery and suppressing a rapid increase in current. The metal layer can include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The metal layer can act as an electrochemical fuse and be cut off in the case of overcurrent, thereby performing a short circuit prevention function. The limit current and the maximum current can be adjusted by adjusting the thickness of the metal layer. The metal layer can be plated or deposited on the base film. As the thickness of the metal layer decreases, the limit current and / or the maximum current of the positive electrode current collector can decrease, and thus the stability of the lithium battery in the case of a short circuit can be improved. A lead tab can be further added on the metal layer for external connection. The lead tab can be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, or the like. During welding, the base film and / or the metal layer can melt, and the metal layer can be electrically connected to the lead tab. To more firmly weld the metal layer and the lead tab, a metal sheet can also be added between the metal layer and the lead tab. The metal sheet can be a thin sheet made of the same material as the metal of the metal layer. The metal sheet can be, for example, a metal foil, a metal mesh, or the like. The metal sheet can be, for example, an aluminum foil, a copper foil, a SUS foil, or the like. After the metal sheet is placed on the metal layer and welded with the lead tab, the lead tab can be welded to the metal sheet / metal layer laminate or to the metal sheet / metal layer / base film laminate. During welding, the base film, the metal layer, and / or the metal sheet can melt, and the metal layer or the metal sheet / metal layer laminate can be electrically connected to the lead tab. The metal sheet and / or the lead tab can also be added to a portion of the metal layer. The thickness of the base film can be, for example, 1 µm to 50 µm, 1.5 µm to 50 µm, 1.5 µm to 40 µm, or 1 µm to 30 µm. By having such a thickness range, the base film can more effectively reduce the weight of the electrode assembly. The melting point of the base film can be, for example, 100 °C to 300 °C, 100 °C to 250 °C, or 100 °C to 200 °C. Because the base film has a melting point in such a range, the base film can melt and easily bond to the lead tab during the welding process of the lead tab. To improve the adhesion of the base film to the metal layer, a surface treatment such as corona treatment can be performed on the base film.The thickness of the metal layer can be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to 1 μm. By having a thickness within such a range, the metal layer can maintain electrical conductivity while ensuring stability of the electrode assembly. The thickness of the metal sheet can be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. By having a thickness within such a range, the metal sheet can enable easier execution of connection between the metal layer and the lead tab. By having such a structure in the positive electrode current collector, the weight of the positive electrode can be reduced, and as a result, the energy density of the positive electrode and the lithium metal battery can be improved.

[0123] (the separator) Next, a separator is prepared which is interposed between the positive electrode and the negative electrode.

[0124] Any separator conventionally used in lithium batteries can be employed. The separator is, for example, one having low resistance to ionic movement of the electrolyte and excellent impregnation ability of the electrolyte. The separator can be selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and can be in the form of a non-woven or woven fabric. In lithium ion batteries, a rollable separator such as polyethylene or polypropylene is used, and in lithium ion polymer batteries, a separator having excellent organic electrolyte impregnation ability is employed.

[0125] The separator is prepared by the following exemplary method; however, it is not necessarily limited to such a method and is adjusted according to the required conditions.

[0126] First, a separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition is directly coated on the top of the electrode and dried to form a separator. Alternatively, the separator composition is cast on a support and dried, and then a separator film peeled from the support is laminated on the top of the electrode to form a separator.

[0127] The polymer used to prepare the separator is not particularly limited, and any polymer that can be used as a binder for an electrode plate can be used. For example, a vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or a mixture thereof can be used.

[0128] (the negative electrode) The negative electrode includes a negative electrode current collector.

[0129] In embodiments of the present disclosure, although not shown in the drawings, the negative current collector can include, for example, a base film and a metal layer disposed on one surface or both surfaces of the base film. The base film can include, for example, a polymer. The polymer can be, for example, a thermoplastic polymer. The polymer can include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer can be an insulating polymer. By including an insulating thermoplastic polymer in the base film, the base film can soften or melt in the event of a short circuit, thereby interrupting the operation of the battery and suppressing a sudden increase in current. The metal layer can include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The metal layer can correspond to, for example, the first metal base. The metal layer can additionally include a coating layer including a second metal. The negative current collector 21 can further include a metal sheet and / or a lead tab. For more specific details regarding the base film, the metal layer, the metal sheet, and the lead tab of the negative current collector 21, refer to the positive current collector. By having such a structure, the negative current collector 21 can reduce the weight of the negative electrode, and as a result, improve the energy density of the negative electrode and the lithium battery.

[0130] A negative active material layer can be formed on the negative current collector. The negative active material layer can be formed as a plated lithium layer after charging. Alternatively, the negative active material layer can be formed using a negative active material during assembly of the battery.

[0131] A method of forming the negative active material layer using a negative active material can be performed in the same manner as forming the positive active material layer, except that a negative active material is used instead of a positive active material.

[0132] The lithium metal battery can further include a thin film on one surface of the negative current collector, the thin film including an element capable of forming an alloy with lithium. The thin film is disposed between the negative current collector and the negative active material layer. The thin film includes, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium can be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not limited thereto, and can include any element that can form an alloy with lithium as known in the art. The thin film can be composed of one of these metals or an alloy of two or more of these metals. By disposing the thin film on one surface of the negative current collector, for example, the plating shape of the first negative active material layer plated between the thin film and the negative active material layer becomes flatter, and the cycle characteristics of the lithium metal battery can be further improved.

[0133] (Electrolyte) An electrolyte according to an embodiment is used.

[0134] The organic electrolyte is prepared, for example, by dissolving a lithium salt in an organic solvent.

[0135] Any organic solvent used in the related art field can be used. The organic solvent can include, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0136] The lithium salt can be any lithium salt used in the related art field. Examples of the lithium salt include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(1≤x≤20, 1≤y≤20), LiCl, LiI, or a mixture thereof. The concentration of the lithium salt can be, for example, 0.1 M to 5.0 M.

[0137] The lithium metal battery according to the embodiment can further include a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof. The solid electrolyte can be, for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0138] The solid electrolyte can be, for example, an oxide-based solid electrolyte. The oxide-based solid electrolyte can be selected from Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 < x < 2, 0 ≤ y < 3), Li3PO4, Li x Ti y (PO4)3(0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3(0 < x < 2, 0 < y < 1, 0 < z < 3), Li 1+x+y (Al,Ga) x (Ti,Ge) 2-x Si y P3-y O 12 (0≤x≤1, 0≤y≤1), Li x La y TiO3(0 3+x La3M2O 12 (wherein, M = Te, Nb, or Zr, and x is an integer of 1 to 10). The solid electrolyte can be prepared by a sintering method or the like. For example, the oxide-based solid electrolyte can be a garnet-type solid electrolyte selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M O 12 (M-doped LLZO, wherein M = Ga, W, Nb, Ta, or Al, and x is an integer of 1 to 10).

[0139] The sulfide-based solid electrolyte can include, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or a combination thereof. The sulfide-based solid electrolyte particles can include Li2S, P2S5, SiS2, GeS2, B2S3, or a combination thereof. The sulfide-based solid electrolyte particles can be Li2S or P2S5. The sulfide-based solid electrolyte particles are known to have high lithium ion conductivity compared to other inorganic compounds. For example, the sulfide-based solid electrolyte can include Li2S or P2S5. When the sulfide solid electrolyte material constituting the sulfide-based solid electrolyte includes Li2S-P2S5, the molar mixing ratio of Li2S to P2S5 can be in a range of about 50:50 to about 90:10. In addition, by adding Li3PO4, a halogen, a halogen compound, Li 2+2x Zn 1-x GeO4 ("LISICON", 0≤x<1), Li 3+ y PO 4-x N x ("LIPON", 0 3.25 Ge 0.25 P 0.75S4 ("ThioLISICON"), Li2O-Al2O3-TiO2-P2O5 ("LATP") added to inorganic solid electrolytes composed of Li2S-P2S5, SiS2, GeS2, B2O3, or combinations thereof can be used as sulfide solid electrolytes. Non-limiting examples of sulfide solid electrolyte materials include: Li2S-P2S5; Li2S-P2S5-LiX (X = halogen element); Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n (0 < m < 10, 0 < n < 10, Z = Ge, Zn, or Ga); Li2S-GeS2; Li2S-SiS2-Li3PO4; and Li2S-SiS2-Li p MO q (0 < p < 10, 0 < q < 10, M = P, Si, Ge, B, Al, Ga, or In). In this regard, sulfide-based solid electrolyte materials can be prepared by a melt quenching method, a mechanical milling method, or the like by processing raw material starting materials of sulfide-based solid electrolyte materials (e.g., Li2S, P2S5, etc.). Further, a calcination process can be performed after the above processing. The sulfide-based solid electrolyte can be amorphous, crystalline, or a mixture of both.

[0140] The polymer solid electrolyte can include, for example, a mixture of a lithium salt and a polymer, or a polymer having an ion conductive functional group. The polymer solid electrolyte can be, for example, a solid polymer electrolyte that is in a solid state at 25℃ and 1 atm. The polymer solid electrolyte can not include, for example, a liquid. The polymer solid electrolyte includes a polymer, and the polymer can be, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methyl methacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(ethylene dioxythiophene) (PEDOT), polypyrrole (PPY), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ketone) (SPEEK), sulfonated poly(arylene ether ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinone)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi + ), or a combination thereof, but is not limited thereto, and all those used as a polymer electrolyte in the related art are feasible. The lithium salt can be any material that can be used as a lithium salt in the related art. The lithium salt can include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, Li(FSO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F2 x+1 SO2)(C y F2 y+1 SO2) (wherein x and y are each 1 to 20), LiCl, LiI, or a mixture thereof. The polymer included in the polymer solid electrolyte can be a compound including, for example, 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer solid electrolyte can be, for example, 1000 daltons or more, 10,000 daltons or more, 100,000 daltons or more, or 1,000,000 daltons or more.

[0141] The gel electrolyte can be, for example, a polymer gel electrolyte. The gel electrolyte can be, for example, in a gel state without including a polymer.

[0142] The polymer gel electrolyte can include, for example, a liquid electrolyte and a polymer, or can include an organic solvent and a polymer having an ionic conductive functional group. The polymer gel electrolyte can be, for example, a polymer electrolyte in a gel state at 25°C and 1 atm. The polymer gel electrolyte can be, for example, in a gel state without including a liquid. The liquid electrolyte used in the polymer gel electrolyte can be, for example, an ionic liquid; a mixture of a lithium salt and an organic solvent; a mixture of a lithium salt and an ionic liquid; a mixture of an ionic liquid and an organic solvent; or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer used in the polymer gel electrolyte can be selected from the polymers used in the polymer solid electrolyte. The organic solvent can be selected from the organic solvents used in the liquid electrolyte. The lithium salt can be selected from the lithium salts used in the polymer solid electrolyte. The ionic liquid refers to a salt or a room temperature molten salt having a melting point at room temperature or lower, consisting only of ions, existing in a liquid state at room temperature. The ionic liquid can include one or more selected from the group consisting of, for example, a) one or more cations selected from the group consisting of ammonium compounds, pyrrolidinium compounds, pyridinium compounds, pyrimidinium compounds, imidazolium compounds, piperidinium compounds, pyrazolium compounds, oxazolium compounds, pyridazinium compounds, phosphonium compounds, sulfonium compounds, triazolium compounds, and mixtures thereof; and b) one or more anions selected from the group consisting of BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , SO4 2- , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N -The polymer solid electrolyte can be formed by impregnation with a liquid electrolyte within a secondary battery, for example, a polymer gel electrolyte. The polymer gel electrolyte can also include inorganic particles. The polymer included in the polymer gel electrolyte can be a compound including, for example, 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer gel electrolyte can be, for example, 500 daltons or more, 1000 daltons or more, 10,000 daltons or more, 100,000 daltons or more, or 1,000,000 daltons or more.

[0143] (lithium metal battery) Referring to Figure 3 The lithium metal battery 1 according to the embodiment includes a cathode 3, the above-described anode 2, and a separator 4. A gel-type polymer electrolyte (not shown) is disposed between the separator and the cathode. The cathode 3, the anode 2, and the separator 4 are wound or folded to form a battery structure 7. The formed battery structure 7 is received in a battery case 5. An organic electrolyte is injected into the battery case 5 and sealed with a cap assembly 6 to complete the lithium metal battery 1. The battery case 5 is cylindrical, but is not necessarily limited to this shape, and can be, for example, prismatic, thin film, etc.

[0144] Referring to Figure 4 and Figure 5 The lithium metal battery 1 according to the embodiment includes a cathode 3, an anode 2, and a separator 4. The separator 4 is disposed between the cathode 3 and the anode 2, and the cathode 3, the anode 2, and the separator 4 are wound or folded to form a battery structure 7. The formed battery structure 7 is received in a battery case 5. The battery structure 7 can include an electrode tab 8 that serves as an electrical path for leading out electrical current generated in the battery structure to the outside. An organic electrolyte is injected into the battery case 5 and sealed to complete the lithium metal battery 1. The battery case 5 is prismatic, but is not necessarily limited to this shape, and can be, for example, cylindrical, thin film, etc.

[0145] A gel-type polymer electrolyte (not shown) can be disposed between the separator 4 and the cathode 3.

[0146] The pouch-type lithium metal battery corresponds to a lithium metal battery in which a pouch is used as a battery case Figure 4The pouch-type lithium metal battery includes one or more battery structures. A separator is disposed between the positive electrode and the negative electrode to form the battery structure. A gel-type polymer electrolyte (not shown) can be disposed between the separator and the positive electrode. The battery structure is impregnated with an electrolyte, housed in a pouch, and sealed to complete the pouch-type lithium metal battery. For example, although not shown in the drawings, the above-described positive electrode, negative electrode, and separator can be simply stacked to form an electrode assembly housed in a pouch, or the electrode assembly can be wound or folded in a jelly-roll form and housed in a pouch. The electrolyte can be an organic electrolyte.

[0147] The lithium metal battery of the present disclosure can be, for example, an all-solid-state lithium metal battery.

[0148] The lithium metal battery of the present disclosure has excellent discharge capacity and life characteristics and a high energy density, and thus can be used, for example, in an electric vehicle (EV). For example, it can be used in a hybrid electric vehicle, such as a plug-in hybrid electric vehicle (PHEV). It is also used in fields requiring a large amount of energy storage. For example, it can be used in an electric bicycle, a power tool, etc.

[0149] The lithium metal battery can be stacked to form a battery module, and a plurality of battery modules can form a battery pack. Such a battery pack can be used in any device requiring high capacity and high output. For example, it can be used in a laptop computer, a smartphone, an electric vehicle, etc. The battery module can include, for example, a plurality of batteries and a frame holding them. The battery pack can include, for example, a plurality of battery modules and bus bars connecting them. The battery module and / or the battery pack can further include a cooling device. A plurality of battery packs can be controlled by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

[0150] [Method for manufacturing lithium metal battery] The method for manufacturing the lithium metal battery according to the embodiment includes the steps of: preparing a negative electrode current collector; a separator; preparing a positive electrode; laminating the negative electrode current collector, the separator, and the positive electrode to prepare an assembly; injecting a composition for forming a gel-type polymer electrolyte into the assembly, the composition for forming a gel-type polymer electrolyte including a monomer for forming a crosslinked polymer and a liquid electrolyte containing an organic solvent and a lithium salt; and crosslinking the injected composition for forming a gel-type polymer electrolyte to manufacture a lithium metal battery including a gel-type polymer electrolyte.

[0151] The monomer for forming a crosslinked polymer includes a multifunctional crosslinking agent having three or more functional groups and a (meth)acrylate compound having a polyethylene glycol moiety. The composition for forming a gel-type polymer electrolyte can include an initiator.

[0152] The process of injecting the composition for forming a gel-type polymer electrolyte into the above assembly can be an impregnation process performed under vacuum, so that the composition for forming a gel-type polymer electrolyte can sufficiently penetrate into the pores of the porous substrate.

[0153] As a method of forming a gel-type polymer electrolyte, a curing method using heat, UV, or high-energy radiation (electron beam, γ-ray) can be used. The curing reaction using heat can be performed at a temperature of 40 to 120°C (for example, 50 to 90°C) for a heat treatment of 30 to 120 minutes.

[0154] The heat treatment can vary depending on the type of the multifunctional crosslinking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety, but can be performed at a temperature of, for example, 40 to 120°C.

[0155] The weight average molecular weight of the multifunctional crosslinking agent having three or more functional groups can be in the range of 200 to 2000, and can be in the range of 200 to 1000, for example, in the range of 200 to 800. The weight average molecular weight of the (meth)acrylate compound having a polyethylene glycol moiety is 300 to 600. If the weight average molecular weight of the multifunctional crosslinking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety is less than the above range, the crosslinking point density in the polymer molecular structure after crosslinking can become too high, which can hinder the free movement of lithium ions. If the weight average molecular weight is greater than the above range, the crosslinking point density in the polymer molecular structure after crosslinking can become too low, which can reduce the electrolyte blocking ability. As used herein, the weight average molecular weight is determined using gel permeation chromatography.

[0156] Based on 100 parts by weight of the composition for forming a gel-type polymer electrolyte, the content of the multifunctional crosslinking agent having three or more functional groups and the (meth)acrylate compound having a polyethylene glycol moiety as monomers for forming a crosslinked polymer is 3 to 5 parts by weight. If the total content of the monomers for forming a crosslinked polymer is less than the above range, the crosslinking degree during crosslinking can become too low, so that the crosslinking properties can not be sufficiently exhibited, and the electrolyte absorption capacity and mechanical properties can be poor. If the total content exceeds the above range, the internal resistance inside the electrode plate can become large, which can cause a capacity reduction during high-rate charging and discharging.

[0157] The composition for forming a gel-type polymer electrolyte can further include a crosslinking agent, a photoinitiator, or the like, to assist the crosslinking of the crosslinkable monomers. The crosslinking agent, the initiator, or the like is not particularly limited as long as they are commonly used in the related art field.

[0158] As the initiator, for example, benzoin ethyl ether or the like can be used.

[0159] The amount of the crosslinking agent, the initiator, and the like used can be within a general range. The content of the initiator can be, for example, 0.1 parts by weight to 10 parts by weight, 0.1 parts by weight to 5 parts by weight, or 0.2 parts by weight to 3 parts by weight, based on 100 parts by weight of the total amount of the monomers used to form the crosslinked polymer. By using the gel-type polymer electrolyte formed as described above, the ionic conductivity close to that of a liquid electrolyte can be maintained, and the gel-type polymer electrolyte inside the positive electrode and the negative electrode can be used to prevent leakage of the liquid electrolyte. The electrolyte can be captured in and remain in the polymer matrix of the gel-type polymer electrolyte, thereby facilitating smooth movement of lithium ions. In addition, since the polymer has excellent electrochemical properties, decomposition reactions of the electrolyte can be inhibited in a range of -1 V to 5 V.

[0160] The following examples and comparative examples describe the inventive concept in more detail. However, the examples are merely illustrative of the inventive concept, and the scope of the inventive concept is not limited thereto.

[0161] Example 1 : TMPTA / PEG-DA (8:2) GPE with 3 wt% cross-linked polymer content (hereinafter: 3 wt% cross-linked polymer) Example 2: TMPTA / PEG-DA (9:1) with 3 wt% cross-linked polymer A laminate was prepared by laminating a polyethylene single layer having a thickness of 20 µm as a separator on top of a copper foil having a thickness of 10 µm as a current collector for a negative electrode, and laminating a positive electrode on the other surface of the separator. The composition for forming a gel-type polymer electrolyte prepared in Example 1 was injected into the prepared laminate, and heat crosslinking was performed in an oven at 70 °C for 1 hour and 30 minutes, thereby preparing a lithium metal battery including a gel-type polymer electrolyte.

[0162] The lithium metal battery had a structure of a positive electrode / gel-type polymer electrolyte (separator) / negative electrode current collector. The pores of the separator contained the gel-type polymer electrolyte.

[0163] A composition for forming a gel-type polymer electrolyte was prepared by mixing trimethylolpropane triacrylate (TMPTA), polyethylene glycol diacrylate (PEG-DA), a liquid electrolyte, and benzoin ethyl ether (Sigma-Aldrich, 240.30 g / mol) as an initiator, which are a multifunctional crosslinking agent having three or more functional groups, as an initiator.

[0164] As the liquid electrolyte, a mixture of diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) in a volume ratio of 2:1 to which 0.6 M of LiBF4 and 0.6 M of lithium difluoro(oxalato)borate (LiDFOB) were added was used.

[0165] The composition for forming a gel-type polymer electrolyte includes 2.4 parts by weight of TMPTA, 0.6 parts by weight of PEG-DA, and 97 parts by weight of a liquid electrolyte, based on 100 parts by weight of the total weight of the composition for forming a gel-type polymer electrolyte excluding the initiator, and the content of the initiator is 5 parts by weight, based on 100 parts by weight of the combined weight of the multifunctional crosslinking agent and PEG-DA.

[0166] The mixed weight ratio of TMPTA to PEG-DA is 8:2, and the weight average molecular weight of PEG-DA is about 550. In the gel-type polymer electrolyte, the content of the crosslinked polymer is 3 wt%, and the content of the liquid electrolyte is 97 wt%.

[0167] The cathode was prepared as follows.

[0168] Li 1.04 Ni 0.88 Co 0.1 Al 0.02 O2 powder and a carbon conductive material (Super-P; Timcal Ltd.) were uniformly mixed at a weight ratio of 90:5. Then, a polyvinylidene fluoride (PVDF) binder solution was added to prepare a cathode active material slurry having a weight ratio of active material, carbon conductive material, and binder of 90:5:5.

[0169] The prepared slurry was coated onto a 15 μm-thick aluminum substrate using a doctor blade, and then vacuum-dried at 120°C. The dried electrode was roll-pressed to form a sheet, thereby manufacturing a cathode.

[0170] Example 3: TMPTA / PEG-DA (7:3) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 1, except that the weight ratio of TMPTA to PEG-DA was changed to 9:1.

[0171] Example 4: TMPTA / PEG-DA (3:1) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 1, except that the weight ratio of TMPTA to PEG-DA was changed to 7:3.

[0172] Example 5: TMPTA / PEG-MA (8:2) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 1, except that the weight ratio of TMPTA to PEG-DA was changed to 3:1.

[0173] Example 6: TMPTA / PEG-MA (9:1) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 1, except that, in the preparation of the gel-type polymer electrolyte composition, polyethylene glycol monoacrylate (PEG-MA) was used instead of polyethylene glycol diacrylate.

[0174] Example 7: TMPTA / PEG-MA (7:3) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 2, except that, in the preparation of the gel-type polymer electrolyte composition, polyethylene glycol monoacrylate (PEG-MA) was used instead of polyethylene glycol diacrylate.

[0175] Example 8: TMPTA / PEG-MA (3:1) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 3, except that, in the preparation of the gel-type polymer electrolyte composition, PEG-MA was used instead of polyethylene glycol diacrylate.

[0176] Example 9: PETTA / PEG-MA (8:2) with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 4, except that, in the preparation of the gel-type polymer electrolyte composition, PEG-MA was used instead of polyethylene glycol diacrylate.

[0177] Comparative Example 1 : TMPTA with 3 wt% cross-linked polymer A lithium metal battery was prepared in the same manner as in Example 1, except that, in the preparation of the gel-type polymer electrolyte composition, pentaerythritol tetramethacrylate (PETTA) was used instead of trimethylolpropane triacrylate (TMPTA).

[0178] Comparative Example 2: Liquid electrolyte (LE) A gel-type polymer electrolyte and a lithium metal battery were prepared in the same manner as in Example 1, except that the gel-type polymer electrolyte composition was prepared by mixing trimethylolpropane triacrylate (TMPTA), an electrolyte composed of a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC) in a weight ratio of 1:1:0.5 and 1.3M LiPF6dissolved therein, and benzoin ethyl ether (Sigma-Aldrich, 240.30 g / mol) as an initiator.

[0179] Evaluation Example 1 : Life at room temperature (25°C) A lithium metal battery was prepared in the same manner as in Example 1, except that a liquid electrolyte was injected instead of the gel-type polymer electrolyte composition prepared in Example 1, and the heat crosslinking step was omitted.

[0180] As the liquid electrolyte, a mixed solvent of diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) in a volume ratio of 2:1 containing 0.6M LiBF4and 0.6M lithium difluoro(oxalato)borate (LiDFOB) was used.

[0181] Evaluation Example 2: Life at room temperature (25°C) The charge / discharge characteristics of the lithium metal batteries of Example 1 and Comparative Examples 1 to 2 were evaluated under the following conditions.

[0182] The battery was charged at a constant current of 0.1C rate until the voltage reached 4.2V (vs. Li) at 25°C, followed by constant voltage charging at 4.2V until the current decreased to 0.05C rate (cut-off). Then, it was discharged at a constant current of 0.1C rate until the voltage decreased to 3.0V (vs. Li) (formation cycle).

[0183] After undergoing the formation cycle, the lithium metal battery was charged at a constant current of 0.2C rate until the voltage reached 4.2V (vs. Li) at 25°C, followed by constant voltage charging at 4.2V until the current decreased to 0.05C rate (cut-off). Subsequently, the battery was discharged at a constant current of 0.2C rate until the voltage reached 3.0V (vs. Li) (1st cycle). The charge / discharge cycle was repeated under the same conditions until the 300th cycle.

[0184] A rest period of 10 minutes was applied after each charge / discharge cycle. Part of the charge / discharge test results at room temperature are shown in Table 1 below, and the capacity retention rate was defined according to Equation 1.

[0185] Equation 1 Capacity retention rate [%] = [discharge capacity at the 300th cycle / discharge capacity at the 1st cycle] x 100 [Table 1]

[0186] As shown in Table 1, the lithium metal battery of Comparative Example 2 exhibited a decrease in capacity retention rate due to side reactions between lithium and electrolyte caused by dendrite growth. The lithium metal battery of Comparative Example 1 showed an improved suppression of the capacity decrease due to the positive electrode interface side reaction and negative electrode dendrite formation, due to the presence of the gel-type polymer electrolyte containing the TMPTA cross-linked polymer. In contrast, the lithium metal battery of Example 1 exhibited an enhanced capacity retention rate compared to both Comparative Example 1 and Comparative Example 2. This improved capacity retention rate is due to the enhanced long-term life characteristics caused by the gel-type polymer electrolyte containing the cross-linked polymer of TMPTA and PEG-DA physically suppressing dendrite growth.

[0187] Evaluation Example 3: High rate capability The charge / discharge characteristics of the lithium metal batteries from Example 4, Example 8, and Comparative Example 2 were evaluated under the following conditions.

[0188] At 25°C, constant current charging was performed at a current rate of 0.1C until the voltage reached 4.2V (vs. Li), followed by constant voltage charging at 4.2V until the current dropped to the cutoff level of 0.05C. Then, constant current discharge was performed at a rate of 0.1C until the voltage dropped to 3.0V (vs. Li) (formation cycle).

[0189] After the formation cycle, constant current charging was performed at a rate of 0.2C until the voltage reached 4.2 V (vs. Li), followed by constant voltage charging at 4.2 V until the current dropped to the cutoff level at a rate of 0.05C. The battery was then discharged at a rate of 0.2C until the voltage reached 3.0 V (vs. Li) (1st cycle). This charge / discharge cycle was repeated under the same conditions until the 100th cycle.

[0190] A 10 minute rest period was applied after each charge / discharge cycle in all cycles.The results of the room temperature charge / discharge tests are shown in Table 2 below.

[0191]

Table 2

[0192] As shown in Table 2, the lithium metal battery of Comparative Example 2 showed a reduced capacity retention rate due to the side reaction between lithium and the electrolyte caused by dendrite growth. In contrast, the lithium metal batteries of Examples 4 and 8 exhibited improved capacity retention rates compared to Comparative Example 2. Notably, the lithium metal battery of Example 4 exhibited excellent capacity retention and capacity characteristics compared to Example 8. This is because the increase in the degree of crosslinking due to the greater number of reactive functional groups crosslinked with the trifunctional crosslinking agent enhances stability, and the gel-type polymer electrolyte physically suppresses dendrite growth, thereby improving long-term life characteristics.

[0193] Evaluation Example 4: Ionic conductivity The lithium metal batteries prepared in Examples 3 and 6 and Comparative Example 1 were charged at a constant current rate of 0.1 C at 25° C. until the voltage reached 4.35 V (relative to Li), and then subjected to constant voltage charging at a cutoff current of 0.05 C at 4.35 V. Subsequently, the batteries were discharged at a constant current of 0.1 C until the voltage reached 2.8 V (relative to Li) (1st cycle, formation cycle).

[0194] After the first cycle, the lithium metal battery was charged at 25°C at a constant current of 0.33 C until the voltage reached 4.35 V (vs. Li), and then maintained at 4.35 V in a constant voltage mode until cutoff at a current of 0.05 C. Subsequently, the battery was discharged at a constant current of 0.2 C until the voltage reached 2.8 V (vs. Li) during discharge (second cycle).

[0195] The 2nd cycle was repeated up to the 7th cycle under the same conditions.

[0196] After completion of the 7th cycle, the lithium metal battery was charged at 0.33C constant current at 25°C until the voltage reached 4.35V (vs. Li), then held at 4.35V in constant voltage mode until the current dropped to 0.05C (cut-off). Subsequently, the battery was discharged at 0.5C constant current until the voltage reached 2.8V (vs. Li) (8th cycle).

[0197] The 8th cycle was repeated up to the 17th cycle under the same conditions.

[0198] After completion of the 17th cycle, the lithium metal battery was charged at 0.33C constant current at 25°C until the voltage reached 4.35V (vs. Li), then held at 4.35V in constant voltage mode until the current dropped to 0.05C (cut-off). Subsequently, the battery was discharged at 1C constant current until the voltage reached 2.8V (vs. Li) (18th cycle).

[0199] The 18th cycle was repeated up to the 25th cycle under the same conditions.

[0200] After completion of the 25th cycle, the lithium metal battery was charged at 0.33C constant current at 25°C until the voltage reached 4.35V (vs. Li), then held at 4.35V in constant voltage mode until the current dropped to 0.05C (cut-off). Subsequently, the battery was discharged at 2C constant current until the voltage reached 2.8V (vs. Li) (26th cycle).

[0201] A rest period of 10 minutes was applied after each charge / discharge cycle.

[0202] A portion of the charge / discharge test results is shown in Table 3 below. The high rate performance was defined according to Equation 2.

[0203] Equation 2 High rate property [%] = [discharge capacity at 26th cycle (2C rate) / discharge capacity at 1st cycle (0.1C rate)] x 100 [Table 3]

[0204] Referring to Table 3, it was confirmed that the performance of the difunctional PEG-DA was superior to that of the monofunctional PEG-MA. In addition, the lithium metal batteries of Example 3 and Example 6 showed improved performance compared to the lithium metal battery of Comparative Example 1. Specifically, the lithium metal battery of Example 3 including the gel-type polymer electrolyte including the cross-linked polymer formed by the reaction of TMPTA and PEG-DA exhibited better high rate characteristics than the lithium metal battery of Example 6 including the gel-type polymer electrolyte including the cross-linked polymer formed by the reaction of TMPTA and PEG-MA. This result is attributed to the fact that PEG-DA increases the cross-linking density of TMPTA, thereby enhancing the oxidation stability and mechanical strength, which in turn improves the overall stability of the system. In addition, the gel-type polymer electrolyte physically suppresses dendrite growth, resulting in improved long-term life characteristics.

[0205] Evaluation Example 5: Charge / discharge characteristics In the lithium metal batteries manufactured according to Example 1 to Example 3 and Comparative Example 1, the ionic conductivity of the gel-type polymer electrolyte was measured using an AC impedance method. In this method, the interfacial resistance and bulk resistance of the battery were monitored in real time by observing the change in impedance. The ionic conductivity of each gel-type polymer electrolyte was calculated using Equation 3 below, and the results are shown in Table 4.

[0206] Equation 3 σ = 1 / Rb x t / A In Equation 3, Rb denotes the resistance of the electrolyte, t is the thickness of the electrolyte film, and A is the area of the electrolyte film.

[0207]

Table 4

[0208] Referring to Table 4, it was found that the gel-type polymer electrolytes of Example 1 to Example 3 exhibited excellent ionic conductivity compared to the gel-type polymer electrolyte of Comparative Example 1.

[0209] However, it was not observed that the ionic conductivity of the gel-type polymer electrolyte linearly increased with the increase in the PEG-DA content, and the most excellent ionic conductivity characteristics were exhibited at a mixed weight ratio of TMPTMA to PEG-DA of 9:1.

[0210] ​ In the lithium metal batteries of Example 1 to Example 3 and Comparative Example 1, the charge / discharge characteristics of the lithium metal battery were evaluated under the following conditions.

[0211] The battery was charged at a constant current of 0.1C rate until the voltage reached 4.2V (vs. Li) at 25°C, followed by a constant voltage charge mode at 4.2V with a cutoff current of 0.05C rate. Then, the battery was discharged at a constant current of 0.1C rate until the voltage dropped to 3.0V (vs. Li) (formation cycle).

[0212] After the formation cycle, the lithium metal battery was charged at a constant current of 0.2C rate until the voltage reached 4.2V (vs. Li) at 25°C, followed by a constant voltage charge at 4.2V with a cutoff current of 0.05C rate. Then, it was discharged at a constant current of 0.2C rate until the voltage dropped to 3.0V (vs. Li) (1st cycle). These cycles were repeated under the same conditions until the 100th cycle.

[0213] Throughout the test, a rest period of 10 minutes was provided after each charge / discharge cycle. Part of the results of the charge / discharge test at room temperature is shown in Table 5 below.

[0214]

Table 5

[0215] As shown in Table 5, the lithium metal batteries of Examples 1 to 3 exhibited improved capacity retention compared to the lithium metal battery of Comparative Example 1. Among them, the lithium metal battery of Example 1 including 20 wt% of PEG-DA showed the highest capacity retention. This improved capacity retention is attributed to the fact that the gel-type polymer electrolyte including the cross-linked polymer of TMPTA and PEG-DA physically suppresses dendrite growth, thereby enhancing long-term life characteristics.

[0216] Although the exemplary embodiments are described in detail with reference to the accompanying drawings, the inventive concept is not limited thereto. It will be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the technical idea set forth in the appended claims, and such variations fall within the technical scope of the inventive concept.

Claims

1. A lithium metal battery comprising: a positive electrode; a negative current collector; and an electrolyte layer disposed between the positive electrode and the negative current collector, wherein the electrolyte layer comprises a gel-type polymer electrolyte, the gel-type polymer electrolyte comprises a cross-linked polymer and a liquid electrolyte comprising an organic solvent and a lithium salt, and the cross-linked polymer comprises a reaction product of a multi-functional cross-linking agent having three or more functional groups and a (meth)acrylate compound having a polyethylene glycol moiety. the multi-functional cross-linking agent having three or more functional groups is trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane ethoxylated triacrylate, trimethylolpropane propoxylated triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylated tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, propoxylated glyceryl triacrylate, or a combination thereof.

2. The lithium metal battery of claim 1, wherein, the (meth)acrylate compound having a polyethylene glycol moiety is polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, glycidyl methacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, or a combination thereof.

3. The lithium metal battery of claim 1, wherein, a mixing weight ratio of the multi-functional cross-linking agent having three or more functional groups to the (meth)acrylate compound having a polyethylene glycol moiety is 9:1 to 2:

1.

4. The lithium metal battery of claim 1, wherein, 5.The lithium metal battery of claim 1, further comprising a negative active material layer, a protective layer, or a combination thereof between the electrolyte layer and the negative current collector. the electrolyte layer further comprises a separator, and 6. The lithium metal battery of claim 1, wherein, the separator comprises a porous substrate. the lithium salt comprises a first lithium salt and a second lithium salt, 7. The lithium metal battery of claim 1, wherein, each of the first lithium salt and the second lithium salt independently comprises a fluorine-containing borate-based lithium salt, the fluorine-containing borate-based lithium salt comprises LiBF4, LiBF3(C2F5), a compound represented by any one of formulas 1 to 12, or a combination thereof, and a content of each of the first lithium salt and the second lithium salt is greater than 0 and less than or equal to 1.2 M, and a content ratio of the first lithium salt to the second lithium salt is 1:9 to 9:1, <Formula 1> <Formula 2> <Formula 3> <Formula 4> <Formula 5> <Formula 6> <Formula 7> <Formula 8> <Formula 9> <Formula 10> <Formula 11> <Formula 12> the organic solvent comprises a first organic solvent and a second organic solvent, 。 8. The lithium metal battery of claim 1, wherein, the first organic solvent comprises a chain carbonate compound, the second organic solvent comprises a cyclic carbonate compound substituted with a substituent, and the substituent comprises a halogen, a cyano group, a nitro group, or a combination thereof. ​ 9. The lithium metal battery of claim 8, wherein, The first organic solvent includes diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, or a combination thereof, and The second organic solvent includes vinylene carbonate substituted with one or more substituents selected from halogen, cyano, and nitro; fluoroethylene carbonate; fluoroethylene carbonate substituted with one or more substituents selected from halogen, cyano, and nitro; or a combination thereof.

10. The lithium metal battery of claim 1, wherein, The electrolyte layer further includes a separator, and The lithium metal battery includes the negative current collector; the separator disposed on the negative current collector; the gel-type polymer electrolyte disposed on the separator; and the positive electrode disposed on the gel-type polymer electrolyte. 11.The lithium metal battery of claim 1, further comprising a lithium metal layer between the negative current collector and the electrolyte layer, and wherein In XPS analysis of a surface of the lithium metal layer, an intensity of a fluorine peak is greater than an intensity of an oxygen peak.

12. The lithium metal battery of claim 1, wherein, The negative current collector includes copper, nickel, nickel-plated copper, stainless steel, iron, cobalt, or an alloy thereof.

13. The lithium metal battery of claim 1, wherein, The positive electrode includes a positive current collector and a positive active material layer, wherein one or both of the positive current collector and the negative current collector includes a base film and a metal layer disposed on one side or both sides of the base film, The base film includes a polymer, and the polymer includes polyethylene terephthalate, polyethylene, polypropylene, polybutylene terephthalate, polyimide, or a combination thereof, and The metal layer includes indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, lithium, or an alloy thereof.

14. The lithium metal battery of claim 1, wherein, The gel-type polymer electrolyte has an ionic conductivity of 0.19 S / cm to 0.5 S / cm.

15. The lithium metal battery of claim 1, wherein, The gel-type polymer electrolyte is present in pores of a separator.

16. The lithium metal battery of claim 1, wherein, The lithium metal battery further includes an electrolyte, and The electrolyte includes a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

17. The lithium metal battery of claim 16, wherein, The solid electrolyte includes an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof, and The gel electrolyte includes a polymer gel electrolyte. 18.A method of manufacturing the lithium metal battery of claim 1, the method comprising the steps of: preparing a negative current collector; preparing an electrolyte layer; preparing a positive electrode; stacking the negative current collector, the electrolyte layer, and the positive electrode to prepare an assembly; injecting a composition for forming a gel-type polymer electrolyte into the assembly, the composition including a multifunctional crosslinking agent having three or more functional groups, a (meth)acrylate compound having a polyethylene glycol moiety, and a liquid electrolyte including an organic solvent and a lithium salt; and crosslinking the injected composition for forming a gel-type polymer electrolyte to prepare a lithium metal battery including a gel-type polymer electrolyte. 19.The method of claim 18, wherein The electrolyte layer includes a separator. 20.The method of claim 18, wherein The crosslinking is performed by heat treatment at 40°C to 120°C. The crosslinking is performed by heat treatment at 40°C to 120

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