Lithium metal battery and manufacturing method therefor

Abstract

The present invention relates to a lithium metal battery and a manufacturing method therefor. More specifically, the lithium metal battery of the present invention comprises: a negative electrode current collector; a separator on the negative electrode current collector; an electrolyte layer on the separator; and a positive electrode on the electrolyte layer, wherein the electrolyte layer may include a gel-polymer electrolyte. The gel-polymer electrolyte may include a crosslinked polymer. The crosslinked polymer may include a repeating unit derived from a crosslinking agent having a hydroxyl group and a double-bond functional group.

Description

Lithium metal battery and method of manufacturing the same

[0001] The present invention relates to a lithium metal battery and a method for manufacturing the same.

[0002]

[0003] Currently available lithium batteries primarily use carbon-based negative electrode active materials, such as graphite. While carbon-based negative electrode active materials offer high stability due to their lack of volume change during charging and discharging, their low capacity necessitates the use of negative electrode active materials with higher capacities.

[0004] Lithium metal, which has a much larger theoretical capacity compared to carbon-based negative electrode active materials, can be used as a negative electrode active material. During charging and discharging, dendrites can form on the surface of lithium metal due to side reactions with the electrolyte, and as these dendrites grow, they can cause a short circuit between the positive and negative electrodes. Consequently, the lifespan characteristics of a lithium metal battery containing lithium metal may be degraded.

[0005]

[0006] The problem that the present invention aims to solve is to provide a lithium metal battery capable of suppressing lithium dendrites and improving lithium ion conductivity.

[0007] Another problem that the present invention aims to solve is to provide a method for manufacturing a lithium metal battery that can suppress lithium dendrites and improve lithium ion conductivity.

[0008]

[0009] A lithium metal battery according to the concept of the present invention comprises a negative electrode current collector; a separator on the negative electrode current collector; an electrolyte layer on the separator; and a positive electrode on the electrolyte layer, wherein the electrolyte layer may comprise a gel-polymer electrolyte. The gel-polymer electrolyte may comprise a cross-linked polymer. The cross-linked polymer may comprise repeating units derived from a cross-linking agent having a hydroxyl group and a double bond functional group. The content of the cross-linked polymer may be 0.5% to 10% by weight based on 100% by weight of the total weight of the gel-polymer electrolyte.

[0010] A method for manufacturing a lithium metal battery according to another concept of the present invention may comprise: providing a negative electrode, a positive electrode, and a separator between the negative electrode and the positive electrode; providing an electrolyte solution between the negative electrode and the positive electrode to impregnate the separator into the electrolyte solution; and performing a thermal crosslinking reaction in the electrolyte solution to form an electrolyte layer. The electrolyte solution may comprise a polymer precursor and a liquid electrolyte. The polymer precursor may comprise a crosslinking agent having a hydroxyl group and a double bond functional group. The content of the polymer precursor relative to the total content of the polymer precursor and the liquid electrolyte in the electrolyte solution may be 0.5% by weight to 10% by weight.

[0011]

[0012] The lithium metal battery according to the present invention can have improved cycle characteristics and lifespan characteristics by using a gel electrolyte with improved ion conductivity.

[0013]

[0014] FIG. 1 is a conceptual diagram briefly illustrating a lithium metal battery according to embodiments of the present invention.

[0015] FIGS. 2 to 4 are each conceptual diagrams briefly illustrating a lithium metal battery according to another embodiment of the present invention.

[0016] FIG. 5 is a conceptual diagram briefly illustrating a cross-linked polymer according to embodiments of the present invention.

[0017] FIGS. 6 to 8 are schematic diagrams illustrating a lithium battery according to one embodiment.

[0018] FIGS. 9a to 9c are cross-sectional views illustrating a method for manufacturing a lithium metal battery according to embodiments of the present invention.

[0019] Figure 10 shows the charge and discharge test results of lithium metal batteries according to the examples and comparative examples.

[0020] Figure 11 shows the ionic conductivity measurement results of gel polymer electrolytes according to the examples and comparative examples.

[0021] Figure 12 shows the resistance measurement results of gel polymer electrolytes according to the examples and comparative examples.

[0022]

[0023] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0024] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0025] Unless otherwise specified in this specification, singular forms may also include plural forms. Additionally, unless otherwise specified, "A or B" may mean "comprising A, comprising B, or comprising A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components to the mentioned components.

[0026] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0027] In this specification, "metal" may include both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0028] In this specification, "alloy" may mean a mixture of two or more metals.

[0029] In this specification, "anode active material" may refer to an anode material capable of undergoing lithiation and delithiation.

[0030] In this specification, "anode active material" may refer to an anode material capable of undergoing lithiation and delithiation.

[0031] In this specification, "lithiation" and "to lithiate" may refer to the process of adding lithium to a positive electrode active material or a negative electrode active material.

[0032] In this specification, "delithiation" and "to delithiate" may refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0033] In this specification, "charge" and "to charge" may refer to the process of providing electrochemical energy to a battery.

[0034] In this specification, "discharge" and "discharge" may refer to the process of removing electrochemical energy from a battery.

[0035] In this specification, "anode" may refer to an electrode where electrochemical reduction and lithiation occur during the discharge process.

[0036] In this specification, "cathode" may refer to an electrode where electrochemical oxidation and delithiation occur during the discharge process.

[0037] Unless otherwise defined in this specification, particle size may be the average particle size. Additionally, particle size refers to the average particle size (D) which means the diameter of the particle whose cumulative volume in the particle size distribution is 50 volume%. 50 It means ). Average particle size (D 50 The measurement can be performed using methods widely known to those skilled in the art, for example, by using a particle size analyzer, or by using transmission electron microscope (TEM) or scanning electron microscope (SEM) images. Alternatively, the measurement may be performed using a measuring device utilizing dynamic light scattering, and after analyzing the data to count the number of particles for each particle size range, the average particle size (D) is calculated from this. 50 ) values ​​can be obtained. Alternatively, it can be measured using the laser diffraction method. When measuring by the laser diffraction method, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasound at approximately 28 kHz is irradiated at an output of 60 W. Then, the average particle size (D) at the 50% reference of the particle size distribution in the measuring device 50 ) can be produced.

[0038]

[0039] FIG. 1 is a conceptual diagram briefly illustrating a lithium metal battery according to embodiments of the present invention. Referring to FIG. 1, the lithium metal battery may include a positive electrode (PEL), a negative electrode (NEL), a separator (SEP), and an electrolyte layer (GPE).

[0040] A lithium metal battery may use lithium metal as a negative electrode active material. In a lithium metal battery, a metal layer containing lithium may be precipitated and dissolved during the charging and discharging process. The lithium-containing metal layer may be formed on the upper surface of the negative electrode current collector (COL1) and within the negative electrode host layer (NHL) described later. As the charging and discharging of the lithium metal battery is repeated, the lithium-containing metal layer may contain impurities remaining in the electrode, decomposition products of the electrolyte, etc.

[0041] The lithium-containing metal layer may have a rough and hard surface due to the inclusion of such impurities. Lithium dendrites may precipitate on the lithium-containing metal layer having such a rough surface. Lithium dendrites continuously grow during the charging and discharging process and can cause a short circuit between the positive electrode (PEL) and the negative electrode (NEL). Furthermore, uneven growth of lithium dendrites on the negative electrode (NEL) during charging can easily cause damage within the cell, and the cell's volume may expand significantly, making long-term operation difficult.

[0042] The positive electrode (PEL) and the negative electrode (NEL) may be spaced apart from each other with a separator (SEP) in between. The separator (SEP) may be placed between the positive electrode (PEL) and the negative electrode (NEL). An electrolyte may be impregnated within the separator (SEP). In one embodiment, the electrolyte may be impregnated within the positive electrode (PEL) and the negative electrode (NEL) as well as the separator (SEP). In one embodiment, the electrolyte may be impregnated within the electrolyte layer (GPE) not only within the separator (SEP) but also within the positive electrode (PEL) and the negative electrode (NEL).

[0043] The electrolyte layer (GPE) may be a medium for transferring lithium ions between the positive electrode (PEL) and the negative electrode (NEL). Within the electrolyte layer (GPE), the lithium ions may pass through a separator (SEP) and move toward the positive electrode (PEL) or the negative electrode (NEL).

[0044]

[0045] NEL

[0046] Referring to FIG. 1, a negative electrode (NEL) for a lithium metal battery may include a negative electrode current collector (COL1). The negative electrode current collector (COL1) may provide a reference surface on which a lithium electrodeposited layer (NAL), to be described later, is formed. The negative electrode current collector (COL1) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative electrode current collector (COL1) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (COL1) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0047] The negative current collector (COL1) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (COL1) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (COL1) may be omitted.

[0048]

[0049] FIG. 2 is a conceptual diagram briefly illustrating a lithium metal battery according to another embodiment of the present invention. Referring to FIG. 2, a lithium electrodeposited layer (NAL) may be formed in the lithium metal battery of FIG. 1 after the operation of an initial cycle. The negative electrode (NEL) of the lithium metal battery after the initial cycle may further include a lithium electrodeposited layer (NAL). The lithium electrodeposited layer (NAL) may be interposed between the negative electrode current collector (COL1) and the electrolyte layer (GPE) described later.

[0050] A lithium electrodeposited layer (NAL) can be formed as lithium metal is plated onto a negative current collector (COL1) by charging a lithium metal battery. The lithium electrodeposited layer (NAL) may comprise lithium metal or a lithium alloy. The lithium alloy may be an alloy of lithium and other metals that can be alloyed with lithium. For example, the lithium alloy may comprise a lithium-silver alloy, a lithium-zinc alloy, a lithium-magnesium alloy, or a lithium-tin alloy.

[0051] The thickness of the lithium electrodeposition layer (NAL) may be, for example, 50 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 1 μm to 50 μm, 1 μm to 40 μm, 5 μm to 40 μm, 1 μm to 35 μm, or 10 μm to 35 μm. By having the lithium electrodeposition layer (NAL) have a thickness within the above-described range, the energy density of the lithium metal battery can be improved.

[0052] According to one embodiment, the thickness of the lithium electrodeposited layer (NAL) at maximum charge may be 35㎛ or less, 30㎛ or less, 28㎛ or less, 10㎛ to 35㎛, 10㎛ to 30㎛, or 10㎛ to 28㎛.

[0053] FIG. 3 is a conceptual diagram briefly illustrating a lithium metal battery according to another embodiment of the present invention. Referring to FIG. 3, the negative electrode (NEL) may further include a protective layer (PTL) on the negative electrode current collector (COL1). The protective layer (PTL) may directly cover the surface of the negative electrode current collector (COL1). The protective layer (PTL) may be interposed between the negative electrode current collector (COL1) and a separator (SEP).

[0054] For example, the protective layer (PTL) may comprise at least one polymer selected from the group consisting of polyvinyl alcohol, polyimide, vinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, carboxymethylcellulose, and styrene-butyrene rubber. The protective layer (PTL) may further comprise an inorganic filler in addition to the polymer. For example, the inorganic filler may be selected from the group consisting of SiO2, Al2O3, Al(OH)3, AlO(OH), TiO2, BaTiO3, ZnO2, Mg(OH)2, Al (Aluminum Nitride), SiC (Silicon Carbide), and BoN (Boron Nitride). For example, the thickness of the protective layer (PTL) may be 1 μm to 20 μm.

[0055] The protective layer (PTL) can reduce side reactions by reducing contact between lithium and the electrolyte layer (GPE), and can suppress lithium dendrite growth by creating a uniform flow of lithium ions to the negative electrode (NEL).

[0056]

[0057] FIG. 4 is a conceptual diagram briefly illustrating a lithium metal battery according to another embodiment of the present invention. Referring to FIG. 4, the negative electrode (NEL) may further include a host layer (HSL) on a negative electrode current collector (COL1). The host layer (HSL) may be interposed between the negative electrode current collector (COL1) and a separator (SEP).

[0058] The host layer (HSL) can provide a space for lithium to be electrodeposited during the charging of the lithium metal battery. For example, the host layer (HSL) may include a space for lithium to be electrodeposited, such as a porous structure. Lithium can be electrodeposited inside the host layer (HSL). The host layer (HSL) can suppress the formation of the lithium electrodeposited layer (NAL) described earlier with reference to FIG. 4. In this way, the host layer (HSL) can suppress lithium dendrites and suppress the increase in the volume of the battery caused by the formation of the lithium electrodeposited layer.

[0059] The host layer (HSL) may include a material having lithium affinity. For example, the host layer (HSL) may include carbon or a metal such as copper. The host layer (HSL) may have a 3D microstructure to maximize the specific surface area and to have porosity. For example, the host layer (HSL) may have a structure such as a sponge or a net.

[0060] The host layer (HSL) may further include a binder for mechanical stability. The binder within the host layer (HSL) can be any polymer used in lithium metal batteries without limitation.

[0061]

[0062] Electrolyte layer (GPE)

[0063] The electrolyte layer (GPE) according to embodiments of the present invention may include a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0064] In one embodiment, the liquid electrolyte is an organic electrolyte. The organic electrolyte may include an organic solvent and a lithium salt. The organic solvent may be selected without limitation as long as it is used as an organic solvent in the art. For example, the organic solvent is 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, dioxolan, 4-methyldioxolan, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0065] Lithium salts may also be selected without restriction if they are used as lithium salts in the relevant technical field. For example, lithium salts include LiSCN, LiN(CN)2, Li(CF3SO2)3C, Li(FSO2)2N(LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiPF3(C2F5)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato) borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), and lithium It may include lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiN(SO2C2F5)2, LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or any combination thereof.

[0066] For example, the concentration of the lithium salt can be 0.1 M to 5.0 M.

[0067] In one embodiment, the solid electrolyte may be a solid polymer electrolyte. The solid polymer electrolyte may comprise a mixture of a lithium salt and a polymer, or may comprise a polymer having ion-conducting functional groups. The solid polymer electrolyte may be in a solid state at 25°C and 1 atm. The solid polymer electrolyte may not contain a liquid.The polymers in the solid polymer electrolyte are, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-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(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), polystyrene sulfonate (PSS), lithium 9,10-diphenylatlasene-2-sulfonate (lithium It may be 9,10-diphenylanthracene-2-sulfonate, DPASLi+) or a combination thereof.The polymer in the solid polymer electrolyte is not limited thereto and can be selected without limitation as long as it is used in the polymer electrolyte in the relevant technical field.

[0068] The lithium salt in the solid polymer electrolyte can be selected from the lithium salts used in the liquid electrolyte described above.

[0069] The polymer in the solid polymer electrolyte may contain 10 or more, 20 or more, 50 or more, or 100 or more repeating units. For example, the weight-average molecular weight of the polymer in the solid polymer electrolyte may be 1,000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0070] In one embodiment, the gel electrolyte may be a gel-polymer electrolyte. According to one embodiment, a separator (SEP) may be impregnated within the gel-polymer electrolyte. The gel-polymer electrolyte may fill the pores within the separator (SEP).

[0071] According to one embodiment of the present invention, the electrolyte layer (GPE) may be a gel-polymer electrolyte. The gel-polymer electrolyte will be described in detail below.

[0072]

[0073] Gel-polymer electrolyte

[0074] The gel-polymer electrolyte may be in a gel state or a semi-solid state. The gel-polymer electrolyte may comprise a liquid electrolyte and a polymer, or may comprise an organic solvent and a polymer having ion-conducting functional groups. The gel-polymer electrolyte may be in a gel state or a semi-solid state at 25 °C and 1 atm.

[0075] For example, a gel-polymer electrolyte may have a gel state without containing liquid. The liquid electrolyte used in the gel-polymer electrolyte may be a mixture of a lithium salt and an organic solvent; a mixture of an ionic liquid and an organic solvent; or a mixture of an ionic liquid, a lithium salt, and an organic solvent.

[0076] The polymer in the gel-polymer electrolyte may be selected from polymers formed from the crosslinking agent described below. The organic solvent in the gel-polymer electrolyte may be selected from the organic solvents used in the liquid electrolyte described above. The lithium salt in the gel-polymer electrolyte may be selected from the lithium salts used in the liquid electrolyte described above.

[0077] For example, the organic solvent is 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, dioxolan, 4-methyldioxolan, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0078] For example, lithium salts include LiSCN, LiN(CN)2, Li(CF3SO2)3C, Li(FSO2)2N(LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiPF3(C2F5)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato) borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), and lithium It may include lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiN(SO2C2F5)2, LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or any combination thereof.

[0079] For example, the concentration of the lithium salt can be 0.1 M to 5.0 M.

[0080] The ionic liquid in the gel-polymer electrolyte may refer to a salt or a room-temperature molten salt that has a melting point below room temperature, is composed solely of ions, and is in a liquid state at room temperature. The ionic liquid comprises a) at least one cation selected from the group consisting of ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, and triazolium cations, and b) BF4 -, PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may include at least one anion selected from the group consisting of

[0081] In one embodiment, a gel-polymer electrolyte can be formed by impregnating a solid polymer electrolyte into a liquid electrolyte.

[0082] In one embodiment, the gel-polymer electrolyte may further include inorganic particles. The polymer in the gel-polymer electrolyte may include 10 or more, 20 or more, 50 or more, or 100 or more repeating units. For example, the weight-average molecular weight of the polymer in the gel-polymer electrolyte may be 500 Dalton or more, 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0083] In one embodiment of the present invention, the gel-polymer electrolyte may include a polymer formed by polymerizing a polyfunctional polymerizable monomer, that is, a crosslinking agent. The crosslinking agent may be a material that is electrochemically stable in an operating environment (e.g., a voltage of about 4.3 V or higher) of a positive electrode using a positive electrode active material having a nickel content of 90 mol% or more.

[0084] The above crosslinking agent may have a weight average molecular weight in the range of 200 to 2,000, or in the range of 200 to 1,000, for example, in the range of 200 to 500. If the weight average molecular weight is less than 200, the density of crosslinking points within the molecular structure of the polymer after crosslinking may be too high, which may restrict the free movement of lithium salts, and if it is greater than 2,000, the density of crosslinking points within the molecular structure of the polymer after crosslinking may be too low, which may reduce the electrolyte blocking ability.

[0085] In one embodiment, the crosslinking agent may include a functional group capable of crosslinking. For example, the crosslinking agent may include two or more hydroxyl groups and double bond functional groups.

[0086] In gel-polymer electrolytes, hydroxyl groups form hydrogen bonds with lithium It can improve ion conductivity by facilitating the transport of ions. Hydrogen bonds formed within the gel-polymer electrolyte enable uniform lithium electrodeposition through the rapid movement of lithium ions on the cathode surface, thereby suppressing the formation of lithium dendrites.

[0087] In one embodiment, the crosslinking agent may have a hydroxyl group and a double bond functional group represented by the following formula 1A or formula 1B:

[0088] <Chemical Formula 1A>

[0089]

[0090] <Chemical Formula 1B>

[0091]

[0092] In the above chemical formula 1A or chemical formula 1B, * is a bonding site with an adjacent atom.

[0093] For example, the crosslinking agent may include at least one selected from the group consisting of hydroxyethyl acrylate (HEA), (hydroxyethyl)methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxybutyl acrylate, pentaerythritol triacrylate (PETA), and dipentaerythritol pentaacrylate (DPEPA).

[0094] In one embodiment, the crosslinking agent may be pentaerythritol triacrylate (PETA) represented by the following chemical formula 1-1.

[0095] <Chemical Formula 1-1>

[0096] .

[0097] The polymer included in the gel-polymer electrolyte may include a cross-linked polymer (CLP).

[0098] The crosslinked polymer (CLP) may include repeating units derived from a crosslinking agent having a hydroxyl group and a double bond functional group.

[0099] FIG. 5 schematically illustrates a cross-linked polymer structure according to embodiments of the present invention. Referring to FIG. 5, the cross-linked polymer (CLP) may include a main chain (M) and a plurality of side chains (S) extending from the main chain (M). For example, the plurality of side chains (S) may include a side chain (S1) extending from the main chain (M) and a side chain (S2) extending from the side chain (S1). Additionally, the main chain (M) and the plurality of side chains (S) of the cross-linked polymer (CLP) may include a terminal portion (E) where the cross-linking reaction or polymerization reaction has ended.

[0100] A cross-linked polymer (CLP) can be formed by cross-linking a polyfunctional polymerizable monomer, i.e., a cross-linking agent. In other words, the cross-linked polymer (CLP) may contain repeating units derived from the cross-linking agent. The cross-linking agent may be a material that is electrochemically stable in the operating environment of a cathode using a cathode active material having a nickel content of 90 mol% or more (e.g., a voltage of about 4.3 V or more).

[0101] In the present invention, the crosslinked polymer may be a reactant produced by the crosslinking reaction of the aforementioned crosslinking agent. Accordingly, the crosslinking agent may be transformed into a polymer structure after the crosslinking reaction and formed as a crosslinked polymer in the gel-polymer electrolyte. At this time, most of the added crosslinking agent is converted into a polymer structure through the crosslinking reaction, and accordingly, the content of the crosslinked polymer in the gel-polymer electrolyte after the crosslinking reaction may be the same as or similar to the content of the initially added crosslinking agent.

[0102] In one embodiment, the content of the crosslinking polymer in the gel-polymer electrolyte may be 0.5 to 10 weight%, 2 to 8 weight%, or 1 to 5 weight% based on 100 weight% of the total weight of the gel-polymer electrolyte. The content of the liquid electrolyte may be 90 to 99.5 weight%, 92 to 98 weight%, or 93 to 97 weight% based on 100 weight% of the total weight of the gel-polymer electrolyte.

[0103] In the above range, ion conductivity can be improved while maintaining the mechanical stability of the gel-polymer electrolyte. If the crosslinked polymer content exceeds the above range, the mechanical stability of the gel-polymer electrolyte may decrease.

[0104] The ionic conductivity of the gel-polymer electrolyte may be 0.25 mS / cm to 0.65 mS / cm. A lithium metal battery having a gel-polymer electrolyte with such ionic conductivity may have improved lifespan characteristics.

[0105] According to one embodiment of the present invention, the gel-polymer electrolyte can improve both the ion conductivity and cell stability of a lithium metal battery by using a crosslinking agent having a hydroxyl group and a double bond functional group. Through this, the initial discharge efficiency and lifespan characteristics of the lithium metal battery can be improved, and thermal stability can be improved.

[0106]

[0107] Separator (SEP)

[0108] Referring again to FIG. 1, depending on the type of lithium metal battery, a separator (SEP) may be provided between the positive electrode (PEL) and the negative electrode (NEL). As such a separator (SEP), polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and of course, mixed multilayer films such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0109] The separator (SEP) may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0110] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0111] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0112] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include, but is not limited to, inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0113] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0114] In one embodiment, the separator (SEP) can be impregnated within the electrolyte layer (GPE).

[0115] The separator (SEP) may contain multiple pores. The electrolyte layer (GPE) may fill each of the pores.

[0116] In one embodiment, the porosity of the separator (SEP) may be 40% to 70%. For example, it may be 40% to 70%, or 50% to 70%.

[0117] In one embodiment, the thickness of the separator (SEP) may be 1 µm to 15 µm. For example, the thickness of the separator (SEP) may be 3 µm to 15 µm, 3 µm to 12 µm, 5 µm to 12 µm, 3 µm to 10 µm, or 5 µm to 10 µm. If the thickness exceeds the above range, the resistance may increase due to an increase in the lithium ion movement path. If the thickness is below the above range, a short circuit may occur due to insufficient mechanical properties.

[0118]

[0119] Anode (PEL)

[0120] The positive electrode (PEL) of a lithium metal battery may include a positive electrode current collector (COL2) and a positive electrode active material layer (PAL) formed on the positive electrode current collector (COL2). The positive electrode active material layer (PAL) includes a positive electrode active material and may further include a binder and / or a conductive material. As an example, the positive electrode active material layer (PAL) may further include an additive capable of acting as a sacrificial electrode.

[0121] The content of the positive active material in the positive active material layer (PAL) may be 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer (PAL). The content of each of the binder and the conductive material may be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer (PAL).

[0122] The above binder can serve to effectively bond the positive active material particles to each other and also to effectively bond the positive active material to the positive current collector (COL2). Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0123] The above conductive material can be used to impart conductivity to the electrode. Any electronically conductive material that does not cause chemical changes in the electrode can be used as the conductive material. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0124] The positive current collector (COL2) may provide a reference surface on which the positive active material layer (PAL) is disposed. The positive current collector (COL2) may comprise, 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 positive current collector (COL2) may comprise a plate or a foil. In another embodiment of the present invention, the positive current collector (COL2) may be omitted. The thickness of the positive current collector (COL2) may be, for example, 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm. In one embodiment, the positive current collector (COL2) may comprise aluminum (Al), but is not limited thereto.

[0125]

[0126] positive electrode active material

[0127] As the positive active material in the positive active material layer (PAL), a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0128] The above composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0129] As an example, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0130] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X 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; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0131] A coating layer may be additionally added to the surface of the aforementioned compound. The coating layer may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of a coating element. The coating layer may be amorphous or crystalline. The coating element within the coating layer may be selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, and Zr. The method of forming the coating layer may be selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method may include, for example, spray coating or immersion methods.

[0132] For example, the above-mentioned positive electrode active material may be a high-nickel positive electrode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in the lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel positive electrode active material can achieve high capacity and can be applied to high-capacity, high-density lithium metal batteries.

[0133]

[0134] lithium metal battery

[0135] Referring to FIG. 6, a lithium metal battery (LBT) according to one embodiment of the present invention may include the above-described positive electrode (PEL), the above-described negative electrode (NEL), and the above-described separator (SEP).

[0136] A positive electrode (PEL), a negative electrode (NEL), and a separator (SEP) can be wound or folded to form a battery structure (BTS). The battery structure (BTS) can be housed in a battery case (CAS). An electrolyte can be injected into the battery case (CAS) to form an electrolyte layer. A lithium metal battery (LBT) can be manufactured by sealing the battery case (CAS) with a cap assembly (CAB). The battery case (CAS) is cylindrical but is not necessarily limited to this shape and may be, for example, prismatic, thin-film, etc.

[0137] Referring to FIG. 7, a lithium metal battery (LBT) according to one embodiment of the present invention may include the above-described positive electrode (PEL), the above-described negative electrode (NEL), and a separator (SEP). A separator (SEP) is disposed between the positive electrode (PEL) and the negative electrode (NEL), and the positive electrode (PEL), the negative electrode (NEL), and the separator (SEP) may be wound or folded to form a battery structure (BTS).

[0138] The formed battery structure (BTS) can be accommodated in a battery case (CAS). It may include an electrode tab (ELT) that serves as an electrical pathway to guide the current formed in the battery structure (BTS) to the outside. An electrolyte layer can be formed by injecting an electrolyte into the battery case (CAS). The battery case (CAS) can be sealed to manufacture a lithium metal battery (LBT). The battery case (CAS) may be prismatic, but is not necessarily limited to this shape and may be, for example, cylindrical, thin-film, etc.

[0139] Referring to FIG. 8, a lithium metal battery (LBT) according to one embodiment of the present invention may include the above-described positive electrode (PEL), the above-described negative electrode (NEL), and a separator (SEP). A separator (SEP) may be disposed between the positive electrode (PEL) and the negative electrode (NEL) to form a battery structure (BTS).

[0140] A battery structure (BTS) can be stacked in a bicell structure and then housed in a battery case (CAS). It may include an electrode tab (ELT) that serves as an electrical pathway to guide the current formed in the battery structure (BTS) to the outside. An electrolyte layer can be formed by injecting an electrolyte into the battery case (CAS). The battery case (CAS) can be sealed to manufacture a lithium metal battery (LBT). The battery case (CAS) may be prismatic, but is not necessarily limited to this shape and may be, for example, cylindrical, thin-film, etc.

[0141] A pouch-type lithium metal battery may correspond to a lithium metal battery (LBT) in each of FIGS. 6 to 8 in which a pouch is used as a battery case (CAS). A pouch-type lithium metal battery may include at least one battery structure (BTS). A pouch-type lithium metal battery may be manufactured by stacking the battery structure (BTS) in a bicell structure, impregnating it into an electrolyte layer, and then housing and sealing it in a pouch.

[0142] For example, the aforementioned anode, cathode, and separator may be simply stacked and accommodated in a pouch in the form of an electrode assembly. The electrode assembly may be wound into a jelly roll or folded and then accommodated in a pouch. An electrolyte layer may be formed by injecting an electrolyte into the pouch.

[0143] Lithium metal batteries have excellent lifespan and high-rate characteristics, so they can be used, for example, in electric vehicles (EVs). For example, they can be used in plug-in hybrid electric vehicles (PHEVs). In addition, they can be used in fields requiring large amounts of power storage. For example, they can be used in electric bicycles, power tools, etc.

[0144] Multiple lithium metal batteries can be stacked to form a battery module. Multiple battery modules can constitute 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 laptops, smartphones, electric vehicles, etc. For example, a battery module may include multiple batteries and a frame that supports them.

[0145] A battery pack may include, for example, a plurality of battery modules and a bus bar connecting them. The battery modules and / or the battery pack may further include a cooling device. A plurality of battery packs may be controlled by a battery management system. The battery management system may include a battery pack and a battery control device connected to the battery pack.

[0146]

[0147] Method for manufacturing a lithium metal battery

[0148] A method for manufacturing a lithium metal battery according to another concept of the present invention may include providing a negative electrode, a positive electrode, and a separator between the negative electrode and the positive electrode; providing an electrolyte solution between the negative electrode and the positive electrode to impregnate the separator in the electrolyte solution; and performing a thermal crosslinking reaction in the electrolyte solution to form an electrolyte layer.

[0149] FIGS. 9a to 9c are cross-sectional views illustrating a method for manufacturing a lithium metal battery according to embodiments of the present invention.

[0150] Referring to Fig. 9a, an assembly can be manufactured in which a separator (SEP) is positioned between the cathode (NEL) and the anode (PEL).

[0151] A negative electrode (NEL), i.e., a negative electrode current collector (COL1), may be provided. The negative electrode current collector (COL1) may comprise at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (COL1) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0152] A positive electrode (PEL) may be provided. The positive electrode (PEL) may include a positive electrode current collector (COL2) and a positive electrode active material layer (PAL). The positive electrode current collector (COL2) may provide a reference surface on which the positive electrode active material layer (PAL) is placed. The positive electrode current collector (COL2) may 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 positive electrode active material layer (PAL) may include a compound capable of reversible intercalation and deintercalation of lithium (a re-intercalated intercalation compound).

[0153] A separator (SEP) may be provided. The separator (SEP) may be laminated between a cathode current collector (COL1) and an anode (PEL). The separator (SEP) may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0154]

[0155] Referring to FIG. 9b, an electrolyte solution (GPC) may be provided to the assembly.

[0156] In one embodiment, the provision of an electrolyte solution (GPC) can be accomplished by filling the electrolyte solution (GPC) within the assembly. For example, the electrolyte solution (GPC) can be filled in the space between the cathode current collector (COL1) and the anode (PEL) in the assembly.

[0157] At this time, the separator (SEP) located between the current collector (COL1) and the anode (PEL) can be impregnated with an electrolyte solution (GPC).

[0158] The electrolyte solution (GPC) may be a precursor for forming the electrolyte layer (GPE) to be described later.

[0159] The electrolyte solution (GPC) may include a liquid electrolyte, a polymer precursor, and a thermal initiator. The polymer precursor may include a crosslinking agent. The crosslinking agent may form a crosslinked polymer through a crosslinking reaction.

[0160] The crosslinking agent, liquid electrolyte, and thermal initiator in the electrolyte solution (GPC) are the same as those described earlier in the gel-polymer electrolyte.

[0161] For example, the crosslinking agent may have a hydroxyl group and a double bond functional group represented by the following chemical formula 1A or chemical formula 1B:

[0162] <Chemical Formula 1A>

[0163]

[0164] <Chemical Formula 1B>

[0165]

[0166] In the above chemical formula 1A or chemical formula 1B, * is a bonding site with an adjacent atom.

[0167] For example, the crosslinking agent may include at least one selected from the group consisting of hydroxyethyl acrylate (HEA), (hydroxyethyl)methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxybutyl acrylate, pentaerythritol triacrylate (PETA), and dipentaerythritol pentaacrylate (DPEPA).

[0168] In one embodiment, the crosslinking agent may be pentaerythritol triacrylate (PETA) represented by the following chemical formula 1-1.

[0169] <Chemical Formula 1-1>

[0170] .

[0171] In one embodiment, the content of the polymer precursor with respect to the total content of the polymer precursor and liquid electrolyte in the electrolyte solution of 100 wt% may be 0.5 to 10 wt%, 2 to 8 wt%, or 1 to 5 wt%. In one embodiment, the content of the liquid electrolyte with respect to the total content of the polymer precursor and liquid electrolyte in the electrolyte solution of 100 wt% may be 90 to 99.5 wt%, 92 to 98 wt%, or 93 to 97 wt% based on the total weight of the gel-polymer electrolyte of 100 wt%.

[0172]

[0173] Referring to FIG. 9c, a thermal crosslinking reaction can be performed on the electrolyte solution (GPC) to form an electrolyte layer (GPE). For example, a heat treatment process (HEP) can be performed on an assembly into which the electrolyte solution (GPC) has been injected. The heat treatment can be performed for 30 minutes to 120 minutes at a temperature of 40 to 120°C, for example, 40°C to 90°C, or 50°C to 90°C.

[0174] An electrolyte layer (GPE) can be formed from an electrolyte solution (GPC) by a heat treatment process (HEP). Specifically, a polymer can be formed by polymerizing the crosslinking agent within the electrolyte solution (GPC).

[0175] The electrolyte layer (GPE) can be in direct contact with the negative current collector (COL1) and the positive active material layer (PAL), as previously explained with reference to FIG. 1. The separator (SEP) can be completely impregnated within the electrolyte layer (GPE). The electrolyte layer (GPE) can fill the pores of the separator (SEP).

[0176] In this way, by using a gel-polymer electrolyte formed by an electrolyte solution (GPC), the ionic conductivity can have a value close to that of a liquid electrolyte. The electrolyte is trapped in the polymer matrix of the gel-polymer electrolyte and retained within the polymer matrix, which can help facilitate the smooth movement of lithium ions.

[0177]

[0178] The present invention will be explained in more detail below through examples. However, these examples are intended to illustrate the invention and the scope of the invention is not limited to these examples.

[0179]

[0180] Example 1

[0181] (Preparation of electrolyte solution)

[0182] The electrolyte solution can be prepared by mixing the crosslinking agent pentaerythritol triacrylate (PETA), a liquid electrolyte, and an initiator.

[0183] As a liquid electrolyte, a 2:1 volume ratio mixed solvent of diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) with 0.6 M LiBF4 and 0.6 M LiDFOB (lithium difluoro(oxalate)borate) added was used.

[0184] The above electrolyte solution contains 4% by weight of PETA and 96% by weight of liquid electrolyte, based on the total weight of the electrolyte solution. 3 parts by weight of an initiator were used based on 100 parts by weight of PETA. Tert-butyl peroxypivalate was used as the initiator.

[0185]

[0186] (Anode manufacturing)

[0187] Li 1.04 Ni 0.8 Co 0.1 Al 0.1O2 A positive electrode active material slurry was prepared by uniformly mixing powder and carbon conductive material (Super-P; Timcal Ltd.) in a weight ratio of 96:2 and then adding a PVDF (polyvinylidene fluoride) binder solution so that the weight ratio of active material:carbon-based conductive material:binder is 96:2:2.

[0188] The prepared slurry was coated onto an aluminum substrate with a thickness of 15 μm using a doctor blade. After drying the coating layer under reduced pressure at 120°C, it was rolled with a roll press to produce a sheet-shaped anode.

[0189]

[0190] (Manufacturing of cells)

[0191] A separator was placed between the previously prepared anode and a 10 μm thick copper foil (negative current collector), and the previously prepared electrolyte solution was injected. A lithium metal battery containing a gel-polymer electrolyte was prepared by thermal crosslinking in a 70°C oven for 2 hours. The lithium metal battery had a structure of anode / gel-type polymer electrolyte (separator) / negative current collector. The pores of the separator are filled with the gel-type polymer electrolyte.

[0192]

[0193] Example 2

[0194] A positive electrode, a separator, and a lithium metal battery containing these were prepared in the same manner as in Example 1, except that the PETA content was 0.5 wt% based on the total weight of the electrolyte solution.

[0195] Specifically, the electrolyte solution contains 0.5% by weight of PETA and 99.5% by weight of liquid electrolyte based on the total weight of the electrolyte solution. 3 parts by weight of the initiator were used based on 100 parts by weight of PETA.

[0196]

[0197] Example 3

[0198] A positive electrode, a separator, and a lithium metal battery containing these were prepared in the same manner as in Example 1, except that the PETA content was 10 wt% based on the total weight of the electrolyte solution.

[0199] Specifically, the electrolyte solution contains 10% by weight of PETA and 90% by weight of liquid electrolyte, based on the total weight of the electrolyte solution. 3 parts by weight of the initiator were used based on 100 parts by weight of PETA.

[0200]

[0201] Comparative Example 1

[0202] A positive electrode, a separator, and a lithium metal battery containing them were prepared in the same manner as in Example 1, except that trimethylolpropane triacrylate (TMPTA) was used as the crosslinking agent instead of PETA when preparing the electrolyte solution.

[0203]

[0204] Comparative Example 2

[0205] A positive electrode, a separator, and a lithium metal battery containing these were prepared in the same manner as in Example 1, except that the PETA content was 0.1 wt% based on the total weight of the electrolyte solution.

[0206] Specifically, the electrolyte solution contains 0.1% by weight of PETA and 99.9% by weight of liquid electrolyte based on the total weight of the electrolyte solution. 3 parts by weight of the initiator were used based on 100 parts by weight of PETA.

[0207]

[0208] Comparative Example 3

[0209] A positive electrode, a separator, and a lithium metal battery containing these were prepared in the same manner as in Example 1, except that the PETA content was 15 wt% based on the total weight of the electrolyte solution.

[0210] Specifically, the electrolyte solution contains 15% by weight of PETA and 85% by weight of liquid electrolyte, based on the total weight of the electrolyte solution. 3 parts by weight of the initiator were used based on 100 parts by weight of PETA.

[0211]

[0212] Evaluation Example 1: Life characteristics

[0213] The charge and discharge characteristics of the lithium metal battery were evaluated under the following conditions.

[0214] Constant current charging was performed at 45°C with a current rate of 0.1 C until the voltage reached 4.3 V (vs. Li), and then cut-off was performed at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, discharge was performed at a constant current rate of 0.1 C until the voltage reached 3.6 V (vs. Li) during discharge (1st formation cycle).

[0215] Subsequently, the lithium metal battery that had undergone the first formation cycle was charged at a constant current rate of 0.2 C at 45°C until the voltage reached 4.3 V (vs. Li), and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 0.2 C until the voltage reached 3.6 V (vs. Li) during discharge (2nd initial capacity verification cycle).

[0216] A lithium metal battery that had undergone a 1st formation cycle and a 2nd initial capacity verification cycle was charged at a constant current rate of 0.33 C at 45°C until the voltage reached 4.3 V (vs. Li), and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 1.0 C until the voltage reached 3.6 V (vs. Li) during discharge (1st cycle). Afterward, the cycle was repeated 300 times under the same conditions.

[0217] In all charge / discharge cycles, a 10-minute pause was taken after each charge / discharge cycle. Life characteristics are defined by <Equation 1>. The results of the charge / discharge experiments are shown in Table 1 and Figure 10 below.

[0218] <Equation 1>

[0219] Life Characteristic [%] = [Discharge capacity in final cycle / Discharge capacity in 1st cycle] × 100

[0220] In Table 1 below, the life characteristic value is calculated using <Equation 1> and represents the number of charge-discharge cycle repetitions at which the capacity retention rate reaches 80%.

[0221]

[0222] Evaluation Example 2: Dose Retention Rate

[0223] The charge and discharge characteristics of the lithium metal battery were evaluated under the following conditions.

[0224] Constant current charging was performed at 45°C with a current rate of 0.1 C until the voltage reached 4.3 V (vs. Li), and then cut-off was performed at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, discharge was performed at a constant current rate of 0.1 C until the voltage reached 3.6 V (vs. Li) during discharge (1st formation cycle).

[0225] Subsequently, the lithium metal battery that had undergone the first formation cycle was charged at a constant current rate of 0.2 C at 45°C until the voltage reached 4.3 V (vs. Li), and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 0.2 C until the voltage reached 3.6 V (vs. Li) during discharge (2nd initial capacity verification cycle).

[0226] 1 st Mars cycle and 2 nd After verifying the initial capacity, the lithium metal battery was charged at a constant current rate of 0.33 C at 45°C until the voltage reached 4.3 V (vs. Li), and then cut off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 1.0 C until the voltage reached 3.6 V (vs. Li) during discharge (1st cycle). Afterward, the cycle was repeated 300 times under the same conditions.

[0227] In all charge / discharge cycles, a 10-minute pause was provided after each charge / discharge cycle, and every 100 cycles, constant current charging was performed at 45°C at a current rate of 0.2 C until the voltage reached 4.3 V (vs. Li), followed by cut-off at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, during discharge, constant current charging was performed at a rate of 0.2 C until the voltage reached 3.6 V (vs. Li). The capacity retention rate is defined by the following <Equations 2> to <Equations 4>.

[0228] <Equation 2>

[0229] Capacity Retention Rate [%] = [RPT discharge capacity at 100 cycles / 2 nd [Discharge capacity during initial capacity verification cycle] × 100

[0230] <Equation 3>

[0231] Capacity Retention Rate [%] = [RPT discharge capacity at 200 cycles / 2 nd Check Initial Capacity [Discharge Capacity] × 100

[0232] <Equation 4>

[0233] Capacity Retention Rate [%] = [RPT discharge capacity at 300 cycles / 2 nd Check Initial Capacity [Discharge Capacity] × 100

[0234] The results of the charge and discharge experiments are shown in Table 1 and Figure 10 below.

[0235] Classification Initial Capacity RPT @100cycle RPT @200cycle RPT @300cycle Lifespan Characteristics 0.2C Ch (mAh) 0.2C Dch (mAh) Capacity (mAh) Capacity Retention Rate (%) Capacity (mAh) Capacity Retention Rate (%) Capacity (mAh) Capacity Retention Rate (%) Cycle# @80% Comparative Example 1 26.4 26.0 19.7 75.9 16.4 63.2 13.3 50.9 111 Comparative Example 2 23.9 23.1 20.2 87.3 16.9 73.0 13.7 59.3 111 Comparative Example 3 23.8 23.1 19.5 84.4 15.7 68.0 7.2 31.164 Example 1 24.2 23.5 21.8 92.8 19.6 83.3 15.7 66.7 174 Example 223.723.120.589.017.676.214.462.6122 Example 324.223.621.892.719.181.216.168.6116

[0236]

[0237] As shown in Table 1 and Figure 10, the lithium batteries of Examples 1 to 3 showed improved capacity retention rate and lifespan characteristics compared to the lithium batteries of Comparative Examples 1 to 3.

[0238] The capacity retention rate of the lithium metal battery according to the embodiments of the present invention is improved because the long-term life characteristics are improved by physically suppressing dendrite growth using a gel polymer electrolyte prepared using a crosslinking agent having a hydroxyl group and a double bond functional group.

[0239]

[0240] Evaluation Example 3: Ionic Conductivity

[0241] The ionic conductivity of the gel polymer electrolyte in the lithium metal batteries prepared according to the examples and comparative examples was evaluated at 25°C and 45°C, respectively.

[0242] The ionic conductivity of the above polymer electrolyte was measured using the AC impedance method. To explain this in more detail, the ionic conductivity and resistance were measured by applying a voltage bias of 10 mV to the polymer electrolyte in a frequency range of 0.1 Hz to 1 MHz, scanning the temperature, and measuring the resistance, and are shown in FIGS. 11 and 12.

[0243] Referring to FIGS. 11 and 12, the gel polymer electrolyte of the example exhibited improved ionic conductivity and resistance at room temperature and high temperature compared to the gel polymer electrolyte of the comparative example.

[0244]

[0245] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. Cathode current collector; Separator on the above-mentioned negative current collector; Electrolyte layer on the separator above; and The electrode on the above electrolyte layer, comprising: The above electrolyte layer comprises a gel-polymer electrolyte, and The above gel-polymer electrolyte includes a cross-linked polymer, and The above-mentioned crosslinked polymer comprises repeating units derived from a crosslinking agent having a hydroxyl group and a double bond functional group, and The content of the above-mentioned crosslinking polymer is 0.5% to 10% by weight based on 100% by weight of the total weight of the gel-polymer electrolyte, Lithium metal battery.

2. In Paragraph 1, A lithium metal battery in which the content of the cross-linked polymer is 1% to 5% by weight based on 100% by weight of the total weight of the gel-polymer electrolyte.

3. In Paragraph 1, A lithium metal battery in which the above double bond functional group is represented by the following chemical formula 1A or chemical formula 1B: <Chemical Formula 1A> <Chemical Formula 1B> In the above chemical formula 1A or chemical formula 1B, * is a bonding site with an adjacent atom.

4. In Paragraph 1, The crosslinking agent comprises at least one selected from the group consisting of hydroxyethyl acrylate (HEA), (hydroxyethyl)methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxybutyl acrylate, pentaerythritol triacrylate (PETA), and dipentaerythritol pentaacrylate (DPEPA). Lithium metal battery.

5. In Paragraph 1, The above crosslinking agent is a lithium metal battery represented by the following chemical formula 1-1: <Chemical Formula 1-1> .

6. In Paragraph 1, The above electrolyte layer further comprises a liquid electrolyte, Lithium metal battery.

7. In Paragraph 6, The above liquid electrolyte includes a lithium salt, and The above lithium salts are LiSCN, LiN(CN)2, Li(CF3SO2)3C, Li(FSO2)2N(LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiPF3(C2F5)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato) borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium Comprising at least one selected from the group consisting of lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiN(SO2C2F5)2, LiCF3SO3, LiAsF6, LiSbF6, and LiClO4, Lithium metal battery.

8. In Paragraph 6, The above liquid electrolyte includes an organic solvent, and The above organic solvent comprises at least one selected from the group consisting of 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, dioxolan, 4-methyldioxolan, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, and dimethyl ether. Lithium metal battery.

9. In Paragraph 1, The above separator is impregnated within the above electrolyte layer, Lithium metal battery.

10. In Paragraph 1, The above separator is a lithium metal battery comprising a plurality of pores.

11. In Paragraph 1, A lithium metal battery in which the porosity of the separator is 40% to 70%.

12. In Paragraph 1, The protective layer between the separator and the negative current collector is further included, A lithium metal battery comprising at least one polymer selected from the group consisting of polyvinyl alcohol, polyimide, vinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, carboxymethylcellulose, and styrene-butyrene rubber.

13. In Paragraph 1, The host layer between the separator and the cathode current collector is further included, The above host layer is configured to provide a space for lithium to be electrodeposited, and The above host layer comprises carbon or metal, in a lithium metal battery.

14. In Paragraph 1, The ionic conductivity of the above gel-polymer electrolyte is 0.25 mS / cm to 0.65 mS / cm, Lithium metal battery.

15. Providing a cathode, an anode, and a separator between the cathode and the anode; Providing an electrolyte solution between the cathode and the anode to impregnate the separator in the electrolyte solution; and The method includes forming an electrolyte layer by performing a thermal crosslinking reaction on the above electrolyte solution, wherein The above electrolyte solution comprises a polymer precursor and a liquid electrolyte, and The above polymer precursor comprises a crosslinking agent having a hydroxyl group and a double bond functional group, and The polymer precursor content is 0.5% to 10% by weight relative to the total content of the polymer precursor and the liquid electrolyte in the electrolyte solution. Method for manufacturing a lithium metal battery.

16. In Paragraph 15, The above thermal crosslinking is performed by heat treatment at 40°C to 90°C, Method for manufacturing a lithium metal battery.

17. In Paragraph 15, A method for manufacturing a lithium metal battery, wherein the above double bond functional group is represented by the following chemical formula 1A or chemical formula 1B: <Chemical Formula 1A> <Chemical Formula 1B> In the above chemical formula 1A or chemical formula 1B, * is a bonding site with an adjacent atom.

18. In Paragraph 15, The crosslinking agent comprises at least one selected from the group consisting of hydroxyethyl acrylate (HEA), (hydroxyethyl)methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxybutyl acrylate, pentaerythritol triacrylate (PETA), and dipentaerythritol pentaacrylate (DPEPA). Method for manufacturing a lithium metal battery.

19. In Paragraph 15, A method for manufacturing a lithium metal battery, wherein the above-mentioned crosslinking agent is represented by the following chemical formula 1-1: <Chemical Formula 1-1> .

20. In Paragraph 15, A method for manufacturing a lithium metal battery, wherein the content of the polymer precursor is 1% to 5% by weight relative to the total content of the polymer precursor and the liquid electrolyte in the electrolyte solution.

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