Negative electrode for lithium metal battery and lithium metal battery comprising same

Abstract

The present invention relates to a negative electrode for a lithium metal battery and a lithium metal battery comprising same, the negative electrode, more specifically, comprising: a negative electrode current collector comprising titanium or an alloy thereof; an oxide layer on the negative electrode current collector, the oxide layer comprising crystalline titanium oxide; and a polymer coating layer on the oxide layer. The polymer coating layer comprises a polymer having a trifluoromethanesulfonylimide (TFSI) functional group.

Description

Anode for a lithium metal battery, and a lithium metal battery comprising the same

[0001] The present invention relates to an anode for a lithium metal battery and a lithium metal battery including the same, and more particularly, to an anode for a lithium metal battery capable of suppressing lithium dendrites and a lithium metal battery including the same.

[0002]

[0003] Lithium batteries currently on the market primarily use carbon-based anode materials, such as graphite. Carbon-based anode materials exhibit no volume change during charge and discharge, contributing to the stability of lithium batteries. However, their low capacity necessitates the use of higher-capacity anode materials.

[0004] Lithium metal, which has a much higher theoretical electrical capacity than carbon-based anode materials, can be used as an anode active material. However, lithium metal can form dendrites on its surface due to side reactions with the electrolyte during charge / discharge, and these dendrites can grow and cause short circuits between the anode and cathode. Consequently, the lifespan of lithium metal batteries containing lithium metal can be reduced.

[0005]

[0006] The problem to be solved by the present invention is to provide a negative electrode for a lithium metal battery capable of suppressing lithium dendrites.

[0007] Another problem to be solved by the present invention is to provide a lithium metal battery having high energy density and excellent lifespan.

[0008]

[0009] According to the concept of the present invention, a negative electrode for a lithium metal battery may include: an negative electrode current collector comprising titanium or an alloy thereof; an oxide layer on the negative electrode current collector, the oxide layer comprising crystalline titanium oxide; and a polymer coating layer on the oxide layer. The polymer coating layer may include a polymer having a trifluoromethanesulfonimide (TFSI) functional group.

[0010] According to another concept of the present invention, a lithium metal battery may include: an anode including an anode current collector, an oxide layer, and a polymer coating layer; an anode including an anode current collector and a positive electrode active material layer; and an electrolyte between the anode and the positive electrode. The polymer coating layer may include a polymer having a TFSI (trifluoromethanesulfonimide) functional group.

[0011] According to another concept of the present invention, a lithium metal battery may include: an anode including an anode current collector, an oxide layer, and a polymer coating layer; a cathode including an anode current collector and a cathode active material layer; and an electrolyte between the anode and the cathode. The anode current collector may include titanium or an alloy thereof, and the oxide layer may include crystalline titanium oxide.

[0012]

[0013] The present invention utilizes a negative electrode for a lithium metal battery having a novel structure, thereby suppressing dendrite formation and enabling uniform deposition of lithium within the negative electrode. A lithium metal battery comprising the negative electrode according to the present invention can exhibit improved cycle characteristics and lifespan characteristics.

[0014]

[0015] FIG. 1 is a schematic diagram illustrating a lithium metal battery according to embodiments of the present invention.

[0016] Figure 2 is an enlarged cross-sectional view of area M of Figure 1.

[0017] Figure 3 is a schematic diagram illustrating a lithium metal battery according to embodiments of the present invention.

[0018] Figures 4 to 6 are schematic diagrams illustrating a lithium battery according to one embodiment.

[0019] Figure 7 is a schematic diagram illustrating a lithium metal battery according to embodiments of the present invention.

[0020] Figure 8a is a scanning electron microscope photograph of the cathode of Example 1.

[0021] Figure 8b is a scanning electron microscope photograph of the cathode of Comparative Example 1.

[0022] Figure 9 is a graph showing the Raman spectrum measured for the oxide layer of the cathode of Example 1.

[0023]

[0024] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0025] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0026] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0027] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0028] In this specification, “metal” may include both metals and metalloids such as silicon and germanium, in either the elemental or ionic state.

[0029] In this specification, “alloy” may mean a mixture of two or more metals.

[0030] In this specification, “positive electrode active material” may mean a positive electrode material capable of undergoing lithiation and delithiation.

[0031] In this specification, “negative electrode active material” may mean a negative electrode material capable of undergoing lithiation and delithiation.

[0032] In this specification, “lithiation” and “lithiating” may refer to a process of adding lithium to a positive electrode active material or a negative electrode active material.

[0033] In this specification, “delithiation” and “delithiate” may refer to a process of removing lithium from a positive electrode active material or a negative electrode active material.

[0034] In this specification, “charging” and “charging” may refer to a process of providing electrochemical energy to a battery.

[0035] In this specification, “discharging” and “discharging” may refer to the process of removing electrochemical energy from a battery.

[0036] In this specification, “positive electrode” may mean an electrode where electrochemical reduction and lithiation occur during a discharge process.

[0037] In this specification, “negative electrode” may mean an electrode where electrochemical oxidation and delithiation occur during a discharge process.

[0038] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0039]

[0040] FIG. 1 is a schematic conceptual diagram illustrating a lithium metal battery according to embodiments of the present invention. FIG. 2 is an enlarged cross-sectional view of area M of FIG. 1. 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).

[0041] Lithium metal batteries can use lithium metal as the anode active material. During the charge / discharge process, a lithium-containing metal layer can precipitate and dissolve between the anode current collector (COL1) and the electrolyte layer (GPE). As the lithium metal battery is repeatedly charged and discharged, the lithium-containing metal layer can contain residual impurities within the electrode, electrolyte decomposition products, and other substances.

[0042] The lithium-containing metal layer may contain these impurities, resulting in a rough and hard surface. Lithium dendrites may precipitate on the lithium-containing metal layer with this rough surface. Lithium dendrites continuously grow during charge and discharge, potentially causing short circuits between the positive electrode (PEL) and negative electrode (NEL). Furthermore, uneven lithium dendrite growth on the negative electrode (NEL) during charging can easily cause damage within the cell, significantly expanding the cell volume and hindering long-term operation.

[0043] The positive electrode (PEL) and the negative electrode (NEL) can be separated from each other with a separator (SEP) therebetween. The separator (SEP) can be disposed between the positive electrode (PEL) and the negative electrode (NEL). The positive electrode (PEL), the negative electrode (NEL), and the separator (SEP) can be in contact with the electrolyte layer (GPE). The separator (SEP) can be impregnated into the electrolyte layer (GPE). In one embodiment, not only the separator (SEP), but also the positive electrode (PEL) and the negative electrode (NEL) can be impregnated into the electrolyte layer (GPE).

[0044] The electrolyte layer (GPE) may be a medium for transporting lithium ions between the positive electrode (PEL) and the negative electrode (NEL). Within the electrolyte layer (GPE), the lithium ions may pass through the separator (SEP) and move toward the positive electrode (PEL) or the negative electrode (NEL).

[0045]

[0046] Positive electrode (PEL)

[0047] A positive electrode (PEL) for 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. For example, the positive electrode active material layer (PAL) may further include an additive that can function as a sacrificial positive electrode.

[0048] The content of the positive active material in the positive active material layer (PAL) may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive active material layer (PAL). The content of each of the binder and the conductive agent may be 0.5 wt% to 5 wt% with respect to 100 wt% of the positive active material layer (PAL).

[0049] The above binder can serve to adhere positive electrode active material particles well to each other and also to adhere positive electrode active material well to positive electrode current collector (COL2). Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0050] The conductive material may be used to impart conductivity to the electrode. Any conductive material that does not cause a chemical change in the electrode and is electronically conductive may be used. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials containing copper, nickel, aluminum, silver, and the like in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0051] Al can be used as the positive electrode collector (COL2), but is not limited thereto.

[0052]

[0053] positive electrode active material

[0054] As the positive active material within the positive active material layer (PAL), a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound) can be used. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0055] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0056] 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 About 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 About 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); Li a 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).

[0057] 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.

[0058] A coating layer may be additionally added to the surface of the above-described compound. The coating layer may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating element of the coating element. The coating layer may be amorphous or crystalline. The coating element in 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 for forming the coating layer may be selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method may include, for example, spray coating or dipping.

[0059] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content 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, based on 100 mol% of metals excluding lithium in the lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium metal batteries.

[0060]

[0061] Separator (SEP)

[0062] Depending on the type of lithium metal battery, a separator (SEP) may be provided between the positive electrode (PEL) and the negative electrode (NEL). The separator (SEP) may be a multilayer film made of polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof. Of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may also be used.

[0063] The separator (SEP) may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0064] The above porous substrate may be a polymer film formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, 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 thereof.

[0065] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0066] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0067] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0068]

[0069] Electrolyte layer (GPE)

[0070] 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.

[0071] 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, 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.

[0072] Lithium salts can be selected without limitation as long as they are used as lithium salts in the relevant technical field. For example, lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, Li(FSO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1SO2)(1≤x≤20, 1≤y≤20), LiCl, LiI or a mixture thereof. For example, the concentration of the lithium salt may be 0.1 M to 5.0 M.

[0073] In one embodiment, the solid polymer electrolyte may include a mixture of a lithium salt and a polymer, or may include a polymer having an ion-conducting functional group. The solid polymer electrolyte may be solid at 25°C and 1 atm. The solid polymer electrolyte may not include a liquid.Polymers in the solid polymer electrolyte include, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), 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), polymethyl methacrylate (PMMA), poly(methylmethacrylate), 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), poly(styrene sulfonate) (PSS), lithium It may be lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi+) or a combination thereof.The polymer in the solid polymer electrolyte is not limited thereto and may be selected without limitation as long as it is used in polymer electrolytes in the relevant technical field.

[0074] The lithium salt in the solid polymer electrolyte can be selected from among the lithium salts used in the liquid electrolyte described above.

[0075] 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 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0076] In one embodiment, the gel electrolyte may be a gel-polymer electrolyte. The gel-polymer electrolyte may have a gel state or a semi-solid state. The gel-polymer electrolyte may include a liquid electrolyte and a polymer, or may include an organic solvent and a polymer having an ion-conducting functional group. The gel-polymer electrolyte may be in a gel state or a semi-solid state at 25°C and 1 atm.

[0077] For example, a gel-polymer electrolyte may have a gel state without containing a 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.

[0078] The polymer in the gel polymer electrolyte may be selected from among the polymers used in the above-described solid polymer electrolyte. The organic solvent in the gel polymer electrolyte may be selected from among the organic solvents used in the above-described liquid electrolyte. The lithium salt in the gel polymer electrolyte may be selected from among the lithium salts used in the above-described liquid electrolyte.

[0079] The ionic liquid in the gel-polymer electrolyte may mean a salt or a molten salt in a liquid state at room temperature, which has a melting point below room temperature and is composed only of ions. The ionic liquid comprises: a) at least one cation selected from the group consisting of ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, and triazolium-based 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 .

[0080] In one embodiment, a gel-polymer electrolyte can be formed by impregnating a solid polymer electrolyte into a liquid electrolyte.

[0081] In one embodiment, the gel polymer electrolyte may further comprise inorganic particles. The polymer within the gel polymer electrolyte may comprise at least 10, at least 20, at least 50, or at least 100 repeating units. For example, the weight average molecular weight of the polymer within the gel polymer electrolyte may be at least 500 Daltons, at least 1000 Daltons, at least 10,000 Daltons, at least 100,000 Daltons, or at least 1,000,000 Daltons.

[0082] In one embodiment of the present invention, the gel polymer electrolyte may include a polymer formed by polymerization of a multifunctional polymerizable monomer, i.e., a cross-linking agent. The cross-linking 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 higher. For example, the crosslinking agent may include at least one selected from the group consisting of pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylated(3) trimethylolpropane triacrylate (PO(3)TMPTA), propoxylated(6) trimethylolpropane triacrylate (PO(6)TMPTA), ethoxylated trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate (Di(trimethylolpropane) tetraacrylate), pentaerythritol triacrylate (PETA), propoxylated glyceryl triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate (THEICTA), and dipentaerythritol hexaacrylate (DPHA).

[0083] The content of the crosslinked polymer in the gel-polymer electrolyte may be 1 to 10 parts by weight, 2 to 8 parts by weight, or 3 to 7 parts by weight based on 100 parts by weight of the total weight of the gel-polymer electrolyte. The content of the liquid electrolyte may be 90 to 99 parts by weight, 92 to 98 parts by weight, or 93 to 97 parts by weight based on 100 parts by weight of the total weight of the gel-polymer electrolyte.

[0084] According to one embodiment of the present invention, the electrolyte layer (GPE) may include the gel-polymer electrolyte described above. The separator (SEP) may be impregnated within the gel-polymer electrolyte. The pores within the separator (SEP) may be filled with the gel-polymer electrolyte.

[0085]

[0086] cathode (NEL)

[0087] Referring back to FIG. 1, the negative electrode (NEL) for a lithium metal battery may include a negative electrode current collector (COL1) and a polymer coating layer (PPL) on the negative electrode current collector (COL1). The negative electrode (NEL) according to the present embodiments may further include an oxide layer (PCL) on the surface of the negative electrode current collector (COL1). The oxide layer (PCL) may be interposed between the negative electrode current collector (COL1) and the polymer coating layer (PPL).

[0088] The negative electrode current collector (COL1) may include titanium (Ti) or an alloy thereof. The negative electrode current collector (COL1) may have a plate or foil shape.

[0089] In one embodiment, the negative electrode current collector (COL1) may include a base film and a metal layer on one or both sides of the base film. The metal layer may include titanium (Ti) or an alloy thereof.

[0090] The base film of the negative electrode current collector (COL1) may include at least one polymer selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), and polyimide (PI). The base film may include an insulating and thermoplastic polymer. The base film of the negative electrode current collector (COL1) may soften or liquefy when a short circuit occurs, thereby blocking battery operation and suppressing a rapid increase in current. The negative electrode current collector (COL1) may additionally include a metal piece and / or a lead tab.

[0091] The oxide layer (PCL) may be provided directly on the surface of the negative electrode current collector (COL1). The oxide layer (PCL) may be an oxide film of a metal constituting the negative electrode current collector (COL1). For example, the oxide layer (PCL) may include titanium oxide. More specifically, the oxide layer (PCL) may include crystalline titanium oxide.

[0092] In one embodiment, the oxide layer (PCL) may be derived from a native oxide layer formed on the surface of the negative electrode current collector (COL1).

[0093] Forming the oxide layer (PCL) may include forming a natural oxide film on the surface of the negative electrode current collector (COL1) and heat-treating the natural oxide film to crystallize it. The natural oxide film may be formed on the surface of the negative electrode current collector (COL1) to a thickness of 2 nm to 10 nm. The natural oxide film may be amorphous.

[0094] The above heat treatment can be performed at a temperature of 200°C to 1200°C. In the heat treatment at 200°C to 700°C, the oxide layer (PCL) can be formed in an anatase crystal phase. In the heat treatment at 700°C to 1200°C, the oxide layer (PCL) can be formed in a rutile crystal phase. The oxide layer (PCL) can include a crystalline layer of an anatase phase, a rutile phase, or a combination thereof. The oxide layer (PCL) can become thicker than a natural oxide film through the above heat treatment. The thickness of the oxide layer (PCL) can be 10 nm to 500 nm, 100 nm to 500 nm, or 300 nm to 500 nm.

[0095] The hardness of rutile can be greater than that of anatase. The hardness of anatase can be greater than that of amorphous. The hardness of the oxide layer (PCL) can be improved through the above heat treatment, i.e., crystallization. The thickness of the oxide layer (PCL) can be increased through the above heat treatment, i.e., crystallization.

[0096] The crystalline oxide layer (PCL) can function as a surface protective film for the negative current collector (COL1). The oxide layer (PCL) can prevent chemical and physical changes in the negative current collector (COL1). The oxide layer (PCL) can prevent the formation of lithium dendrites on the negative current collector (COL1) and induce uniform lithium deposition.

[0097] Referring to FIGS. 1 and 2, the polymer coating layer (PPL) may include a polymer configured to suppress the formation of lithium dendrites. The polymer coating layer (PPL) may include a trifluoromethanesulfonimide (TFSI)-based polymer. Specifically, the polymer coating layer (PPL) may include a polymer having at least one TFSI functional group bonded to a hydrocarbon backbone (PBB). Lithium ions may be bonded to the TFSI functional group.

[0098] The hydrocarbon backbone (PBB) may have a linear polymer form, a branched polymer form, a network polymer form, or a ladder polymer form. The polymer of the polymer coating layer (PPL) may be a homopolymer, a copolymer, or a combination thereof, and is not particularly limited.

[0099] For example, the polymer coating layer (PPL) may include PMTFSI (Poly(methacrylate TSFI)), PSTFSI (Poly(4-styrenesulfonyl TSFI)), or a combination thereof. The polymer of the polymer coating layer (PPL) may have a weight average molecular weight of 1,000 to 100,000.

[0100] In one embodiment of the present invention, the polymer coating layer (PPL) may further include an oxidizing agent (MNT). The oxidizing agent (MNT) may be uniformly dispersed within the polymer of the polymer coating layer (PPL). The oxidizing agent (MNT) may include a nitrate. The oxidizing agent (MNT) may include an alkali metal nitrate or an alkaline earth metal nitrate. For example, the oxidizing agent (MNT) may include at least one selected from the group consisting of LiNO3, KNO3, and Fe(NO3)2.

[0101] In one embodiment, the oxidizing agent (MNT) may be present in a dissolved form within the polymer coating layer (PPL). In another embodiment, the oxidizing agent (MNT) may be present in an insoluble form within the polymer coating layer (PPL), for example, in the form of particles.

[0102] Nitrate (NO3) of oxidizing agent (MNT) - ) can improve the electrodeposition shape of lithium on the negative electrode collector (COL1). The nitrate (NO3) of the oxidizing agent (MNT) - ) can prevent the formation of lithium dendrites. In a comparative example of the present invention, when a metal such as copper is used for the negative electrode current collector (COL1), the nitrate (NO3) of the oxidizing agent (MNT) - ) causes a problem of deteriorating the battery by dissolving copper from the negative electrode current collector (COL1). Meanwhile, according to embodiments of the present invention, titanium may be used for the negative electrode current collector (COL1) and a crystalline oxide layer (PCL) may be provided on the surface of the negative electrode current collector (COL1). Accordingly, the present invention can effectively prevent the negative electrode current collector (COL1) from reacting with the oxidizing agent (MNT) in the polymer coating layer (PPL).

[0103]

[0104] FIG. 3 is a schematic conceptual diagram illustrating a lithium metal battery according to embodiments of the present invention. Referring to FIG. 3, the lithium metal battery of FIG. 1 may have a lithium electrodeposited layer (NAL) formed after the initial cycle of operation. 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 oxide layer (PCL) and the polymer coating layer (PPL).

[0105] A lithium electrodeposited layer (NAL) may be formed by depositing lithium metal between a oxide layer (PCL) and a polymer coating layer (PPL) during charging of a lithium metal battery. The lithium electrodeposited layer (NAL) may include lithium metal or a lithium alloy. The lithium alloy may be an alloy of lithium and another metal capable of alloying with lithium. For example, the lithium alloy may include a lithium-silver alloy, a lithium-zinc alloy, a lithium-magnesium alloy, or a lithium-tin alloy.

[0106] The thickness of the lithium electrodeposited layer (NAL) can 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. The energy density of the lithium metal battery can be improved by the lithium electrodeposited layer (NAL) having a thickness in the above-described range.

[0107] In one embodiment, the thickness of the lithium electrodeposited layer (NAL) at maximum charge may be 35 μm or less, 30 μm or less, 28 μm or less, 10 μm to 35 μm, 10 μm to 30 μm, or 10 μm to 28 μm.

[0108] According to embodiments of the present invention, the negative electrode current collector (COL1) may include titanium, and an oxide layer (PCL) that functions as a protective film may be provided on the surface of the negative electrode current collector (COL1). A polymer coating layer (PPL) that suppresses the formation of lithium dendrites may be provided on the oxide layer (PCL). As a result, the shape of the lithium electrodeposited layer (NAL) formed by the initial electrodeposition of lithium may have a very uniform thickness without dendrites.

[0109]

[0110] lithium metal battery

[0111] Referring to FIG. 4, a lithium battery (LBT) according to an embodiment of the present invention may include the aforementioned positive electrode (PEL), the aforementioned negative electrode (NEL), and the separator (SEP). The positive electrode (PEL), the negative electrode (NEL), and the separator (SEP) may be wound or folded to form a battery structure (BTS). The battery structure (BTS) may be accommodated in a battery case (CAS). An electrolyte layer may be formed by injecting an electrolyte into the battery case (CAS). The lithium battery (LBT) may be manufactured by sealing the battery case (CAS) with a cap assembly (CAB). The battery case (CAS) may be cylindrical, but is not necessarily limited to this shape, and may be, for example, square, thin-film, etc.

[0112] Referring to FIG. 5, a lithium 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 separator (SEP). The 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).

[0113] The formed battery structure (BTS) can be accommodated in a battery case (CAS). An electrode tab (ELT) that serves as an electrical path for conducting the current formed in the battery structure (BTS) to the outside can be included. 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 battery (LBT). The battery case (CAS) is not necessarily limited to a square shape, but may be, for example, cylindrical, thin-film, etc.

[0114] Referring to FIG. 6, a lithium battery (LBT) according to one embodiment of the present invention may include the aforementioned positive electrode (PEL), the aforementioned negative electrode (NEL), and the separator (SEP). The separator (SEP) may be disposed between the positive electrode (PEL) and the negative electrode (NEL) to form a battery structure (BTS).

[0115] A battery structure (BTS) can be stacked in a bi-cell structure and then accommodated in a battery case (CAS). An electrode tab (ELT) that serves as an electrical path for conducting current formed in the battery structure (BTS) to the outside can be included. 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 battery (LBT). The battery case (CAS) is not necessarily limited to a square shape, and may be, for example, cylindrical, thin-film, etc.

[0116] A pouch-type lithium battery may correspond to a lithium battery (LBT) of each of FIGS. 4 to 6 that uses a pouch as a battery case (CAS). The pouch-type lithium battery may include at least one battery structure (BTS). The battery structure (BTS) may be laminated in a bi-cell structure, then impregnated with an electrolyte layer, and accommodated and sealed in a pouch to manufacture a pouch-type lithium battery.

[0117] For example, the above-described positive electrode, negative electrode, and separator may be simply laminated and housed in a pouch in the form of an electrode assembly. The electrode assembly may be wound or folded into a jelly roll shape and then housed in the pouch. An electrolyte layer may be formed by injecting an electrolyte solution into the pouch.

[0118] Lithium batteries have excellent cycle life and high-rate characteristics, making them suitable for use in electric vehicles (EVs). For example, they can be used in plug-in hybrid electric vehicles (PHEVs). They can also be used in applications requiring large amounts of power storage, such as electric bicycles and power tools.

[0119] Multiple lithium batteries can be stacked to form a battery module. Multiple battery modules can form a battery pack. Such a battery pack can be used in any device requiring high capacity and output. Examples include laptops, smartphones, and electric vehicles. For example, a battery module may include multiple batteries and a frame supporting them.

[0120] 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. The 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.

[0121]

[0122] A lithium battery including a solid electrolyte is described in more detail below. A lithium metal battery according to one embodiment of the present invention may be, for example, an all-solid-state lithium battery including a solid electrolyte. By including the aforementioned negative electrode, the all-solid-state lithium battery can have improved capacity and superior lifespan characteristics.

[0123] FIG. 7 is a schematic conceptual diagram illustrating a lithium metal battery according to embodiments of the present invention. Referring to FIG. 7, the all-solid-state lithium battery may include a positive electrode (PEL), the aforementioned negative electrode (NEL), and a solid electrolyte layer (SEL) interposed between the positive electrode (PEL) and the negative electrode (NEL). The positive electrode (PEL) may include a positive electrode current collector (COL2) and a positive electrode active material layer (PAL). The positive electrode active material layer (PAL) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder. The positive electrode active material, the conductive material, and the binder may be substantially the same as or similar to those described in the positive electrode active material layer (PAL) with reference to FIG. 1 above.

[0124] The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a 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 (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may include at least one selected from (0≤x≤2).

[0125] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x (0≤x≤2) may be an argyrodite-type compound including at least one selected from. In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0126] The solid electrolyte in the positive active material layer (PEL) may have a smaller average particle diameter (D50) than the solid electrolyte in the solid electrolyte layer (SEL), which will be described later. For example, the average particle diameter (D50) of the solid electrolyte in the positive active material layer (PEL) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle diameter (D50) of the solid electrolyte in the solid electrolyte layer (SEL).

[0127] When the total amount of the positive electrode active material, the solid electrolyte, the conductive material, and the binder is 100 parts by weight, the positive electrode active material layer (PEL) may include 85 parts by weight to 92 parts by weight of the positive electrode active material. The positive electrode active material layer (PEL) may include 0.5 parts by weight to 1.5 parts by weight of the binder.

[0128] Within the positive active material layer (PEL), the conductive material may be present in an amount of 1 to 50 parts by weight relative to 100 parts by weight of the solid electrolyte. If the conductive material is present in an amount less than 1 part by weight relative to 100 parts by weight of the solid electrolyte, the electrical conductivity of the positive active material layer (PEL) may deteriorate. If the conductive material is present in an amount greater than 50 parts by weight relative to 100 parts by weight of the solid electrolyte, the conductive material ratio may be excessively high, and a covering layer covering the surface of the solid electrolyte may not be properly formed.

[0129] According to embodiments, the positive electrode active material layer (PEL) may further include at least one additive selected from the group consisting of a filler, a coating agent, a dispersant, and an ion conductive additive, in addition to the positive electrode active material, solid electrolyte, conductive agent, and binder described above.

[0130] The solid electrolyte layer (SEL) is disposed between the positive electrode (PEL) and the negative electrode (NEL) and may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (SEL) may be the same as or similar to the solid electrolyte in the positive electrode active material layer (PEL) described above.

[0131] The solid electrolyte layer (SEL) may further include a binder. The binder in the solid electrolyte layer (SEL) may be, but is not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or the like. The binder in the solid electrolyte layer (SEL) may be the same as or similar to the binder in the positive active material layer (PAL).

[0132] The negative electrode (NEL) of the all-solid-state lithium battery may be substantially the same as or similar to the negative electrode (NEL) described above with reference to FIG. 1.

[0133]

[0134] Hereinafter, the present invention will be described in more detail through examples. However, these examples are intended to exemplify the present invention and the scope of the present invention is not limited to these examples.

[0135] Example 1

[0136] Ti foil (thickness: 10 μm) was used as the negative electrode current collector. A natural oxide film was formed on the surface of the Ti foil. The Ti foil was heat-treated in an electric furnace at approximately 600°C for 2 hours. The thickness of the oxide layer after heat treatment was approximately 500 nm.

[0137] A PMTFSI (Poly(methacrylate TSFI)) aqueous solution in slurry form was coated on a heat-treated Ti foil. The coated slurry was dried to form a polymer coating layer on the oxide layer.

[0138]

[0139] Example 2

[0140] A negative electrode was manufactured according to the same method as Example 1, except that slurry coating was performed by adding more LiNO3 to the PMTFSI aqueous solution.

[0141]

[0142] Example 3

[0143] A negative electrode was manufactured according to the same method as in Example 1, except that a slurry-type PSTFSI (Poly(4-styrenesulfonyl TSFI)) aqueous solution was used.

[0144]

[0145] Example 4

[0146] A negative electrode was manufactured according to the same method as in Example 1, except that slurry coating was performed by further adding LiNO3 to a slurry-type PSTFSI (Poly(4-styrenesulfonyl TSFI)) aqueous solution.

[0147]

[0148] Comparative Example 1

[0149] Bare Cu foil (thickness: 10 um) was used as the negative electrode collector.

[0150]

[0151] Comparative Example 2

[0152] Bare Ti foil (thickness: 10 um) was used as the negative electrode collector.

[0153]

[0154] Comparative Example 3

[0155] Cu foil (thickness: 10 μm) was used as the negative electrode collector. A slurry-type PMTFSI (Poly(methacrylate TSFI)) aqueous solution was coated on the Cu foil. The coated slurry was dried to form a polymer coating layer on the Cu foil.

[0156]

[0157]

[0158] Production Example 1: Manufacturing of a Lithium Metal Battery

[0159] (Polar electrode manufacturing)

[0160] Li 1.04 Ni 0.8 Co 0.1 Al 0.1O2 A positive electrode active material slurry was prepared by uniformly mixing the powder and carbon conductive material (Super-P; Timcal Ltd.) at a weight ratio of 96:2, and then adding a PVDF (polyvinylidene fluoride) binder solution to obtain a weight ratio of active material:carbon conductive material:binder = 96:2:2.

[0161] The prepared slurry was coated on a 15 ㎛ thick aluminum substrate using a doctor blade. The coating layer was dried under reduced pressure at 120°C and then rolled using a roll press to produce a positive electrode in the form of a sheet.

[0162] (Manufacturing of coin cells)

[0163] A polypropylene separator (Celgard 3510) was placed between the previously manufactured positive and negative electrodes (Examples 1 to 4 and Comparative Examples 1 to 3), and a composition for forming a gel-polymer electrolyte was injected. A lithium metal battery including a gel-polymer electrolyte was manufactured by thermally cross-linking in an oven at 70°C for 2 hours. The lithium metal battery had a structure of positive electrode / gel-type polymer electrolyte (separator) / negative electrode current collector. The pores of the separator were filled with a gel-type polymer electrolyte.

[0164] A composition for forming a gel-polymer electrolyte can be prepared by mixing a crosslinking agent, dipentaerythritol hexaacrylate (DPHA), a liquid electrolyte, and an initiator.

[0165] As a liquid electrolyte, a 2:1 volume ratio mixed solvent of diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) was used, in which 0.6 M LiBF4 and 0.6 M LiDFOB (lithium difluoro(oxalate)borate) were added.

[0166] The above composition contains 3 parts by weight of DPHA and 97 parts by weight of a liquid electrolyte based on 100 parts by weight of the total weight of the composition. 3 parts by weight of the initiator was used based on 100 parts by weight of DPHA. tert-butyl peroxypivalate was used as the initiator.

[0167]

[0168] Evaluation Example 1: Scanning Electron Microscope (SEM) Analysis

[0169] In a lithium metal battery using the negative electrode of Example 1, a scanning electron microscope analysis was performed on the negative electrode surface after the initial cycle. In a lithium metal battery using the negative electrode of Comparative Example 3, a scanning electron microscope analysis was performed on the negative electrode surface. The analysis results are shown in Figs. 8a and 8b. Fig. 8a is an electron microscope image of the negative electrode of Example 1, and Fig. 8b is an electron microscope image of the negative electrode of Comparative Example 1.

[0170] As shown in Fig. 8b, it was confirmed that the negative electrode of Comparative Example 1 had many dendrites formed in a scale-like shape. As shown in Fig. 8a, it was confirmed that the negative electrode of Example 1 had almost no dendrite formation. In addition, it was confirmed that the negative electrode of Example 1 had a lithium electrodeposition layer formed with a uniform thickness.

[0171]

[0172] Evaluation Example 2: Raman Spectrum Analysis

[0173] The Raman spectrum of the oxide layer of the cathode of Example 1 was measured using a Raman spectrophotometer (TOKYO INSTRUMENT INC, NANOFINDER 30), and the results are shown in Fig. 9.

[0174] Referring to Fig. 9, it was confirmed that the titanium oxide film of the cathode of Example 1 had a characteristic peak of a rutile crystal phase. In other words, it can be confirmed that the oxide film in the cathode of Example 1 is a crystalline titanium oxide film.

[0175]

[0176] Evaluation Example 3: Life Characteristics

[0177] The charge / discharge characteristics of a lithium metal battery were evaluated under the following conditions.

[0178] The battery was charged at a constant current of 0.1 C rate at 45°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 3.6 V (vs. Li) (1 st Mars (formation) cycle).

[0179] After the first Mars cycle, the lithium metal battery was charged at a constant current of 0.2 C rate at 25°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.2 C rate until the voltage reached 3.6 V (vs. Li) (2 nd Mars (formation) cycle).

[0180] The lithium metal battery, which had undergone a Mars cycle, was charged at a constant current of 0.33 C rate at 25°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 1.0 C rate until the voltage reached 3.6 V (vs. Li) (1 st cycle). The cycle was then repeated 100 times under the same conditions.

[0181] In all charge / discharge cycles, a 10-minute pause was provided after each charge / discharge cycle. The capacity retention rate is defined by Equation 1 below. The results of the room-temperature charge / discharge experiments are shown in Table 1 below.

[0182] <Formula 1>

[0183] Capacity retention rate [%] = [Discharge capacity at 100th cycle / Discharge capacity at 1st cycle] × 100

[0184] Cathode capacity retention rate (%)Example 1Ti / Oxide layer / PMTFSI polymer coating layer 92.20Example 2Ti / Oxide layer / PMTFSI polymer coating layer + nitrate 92.93Example 3Ti / Oxide layer / PSTFSI polymer coating layer 92.77Example 4Ti / Oxide layer / PSTFSI polymer coating layer + nitrate 93.35Comparative Example 1Cu 88.32Comparative Example 2Ti 89.04Comparative Example 3Cu / PMTFSI polymer coating layer 88.56

[0185] As shown in Table 1, the lithium batteries of Examples 1 to 4 had improved capacity retention rates compared to the lithium batteries of Comparative Examples 1 to 3. In particular, it can be confirmed that the lithium battery of Example 1 had improved capacity retention rates compared to the lithium battery of Comparative Example 3. In addition, it can be confirmed that the lithium battery of Example 2 had improved capacity retention rates more than the lithium battery of Example 1. The reason why the capacity retention rates of the lithium metal batteries according to the examples of the present invention are improved is because, first, dendrites can be effectively suppressed by using titanium coated with a polymer layer. Furthermore, it was confirmed that when the polymer layer further includes nitrate, dendrites can be suppressed more effectively.

[0186] Meanwhile, even though a polymer layer was coated on the copper current collector as in Comparative Example 3, the copper current collector showed a lower lifespan characteristic compared to the titanium current collector.

[0187]

[0188] Evaluation Example 4: High-rate characteristics

[0189] The high-rate characteristics of lithium metal batteries were evaluated under the following conditions.

[0190] The lithium metal battery was charged at a constant current of 0.1 C rate at 45°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 3.6 V (vs. Li) (1 st cycle, Mars (formation) cycle).

[0191] 1 st The cycled lithium battery was charged at a constant current of 0.2 C at 45°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.2 C until the voltage reached 3.6 V (vs. Li) (2 nd cycle).

[0192] 2 nd The cycled lithium battery was charged at a constant current of C / 3 at 25°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 1.0 C rate until the voltage reached 3.6 V (vs. Li) (3 rd cycle).

[0193] In all the above charge / discharge cycles, a pause of 10 minutes was allowed after each charge / discharge cycle.

[0194] Some of the results of the above charge-discharge experiment are shown in Table 2 below. The high-rate characteristics are defined by Equation 2 below.

[0195] <Formula 2>

[0196] High rate characteristic [%] = [3 rd Discharge capacity in cycle (1C rate) / 1 stDischarge capacity in cycle (0.1C rate)] × 100

[0197] Classification Cathode High Rate Characteristics (%) Example 1 Ti / Oxide Layer / PMTFSI Polymer Coating Layer 83.1 Example 2 Ti / Oxide Layer / PMTFSI Polymer Coating Layer + Nitrate 84.1 Example 3 Ti / Oxide Layer / PSTFSI Polymer Coating Layer 83.4 Example 4 Ti / Oxide Layer / PSTFSI Polymer Coating Layer + Nitrate 84.9 Comparative Example 1 Cu 82.5 Comparative Example 2 Ti 83.0 Comparative Example 3 Cu / PMTFSI Polymer Coating Layer 79.9

[0198] Referring to Table 2, it can be confirmed that the high-rate characteristics of the lithium metal batteries of Examples 1 to 4 are improved compared to the lithium metal battery of Comparative Example 3. This is because dendrites can be effectively suppressed by using titanium coated with a polymer layer.

[0199]

[0200] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. A cathode current collector comprising titanium or an alloy thereof; an oxide layer on the negative electrode current collector, the oxide layer comprising crystalline titanium oxide; and Including a polymer coating layer on the above oxide layer, A negative electrode for a lithium metal battery, wherein the polymer coating layer comprises a polymer having a TFSI (trifluoromethanesulfonimide) functional group.

2. In paragraph 1, A negative electrode for a lithium metal battery, further comprising a lithium electrodeposition layer between the oxide layer and the polymer coating layer.

3. In paragraph 1, A negative electrode for a lithium metal battery, wherein the polymer coating layer further comprises an oxidizer.

4. In paragraph 3, A negative electrode for a lithium metal battery, wherein the oxidizing agent comprises nitrate.

5. In paragraph 1, The above crystalline titanium oxide is a negative electrode for a lithium metal battery having an anatase phase, a rutile phase, or a combination thereof.

6. In paragraph 1, A negative electrode for a lithium metal battery, wherein the thickness of the oxide layer is 10 nm to 500 nm.

7. In paragraph 1, A negative electrode for a lithium metal battery, wherein the above oxide layer is derived from a natural oxide film of the negative electrode current collector.

8. In paragraph 1, A negative electrode for a lithium metal battery, wherein the polymer coating layer comprises PMTFSI (Poly(methacrylate TSFI)), PSTFSI (Poly(4-styrenesulfonyl TSFI)), or a combination thereof.

9. A cathode comprising a cathode current collector, an oxide layer and a polymer coating layer; A cathode comprising a cathode current collector and a cathode active material layer; and Including an electrolyte between the cathode and the anode, A lithium metal battery, wherein the polymer coating layer comprises a polymer having a TFSI (trifluoromethanesulfonimide) functional group.

10. In paragraph 9, A lithium metal battery, wherein the negative electrode current collector comprises titanium or an alloy thereof.

11. In paragraph 9, A lithium metal battery, wherein the oxide layer comprises crystalline titanium oxide.

12. In paragraph 9, A lithium metal battery, wherein the polymer coating layer further comprises nitrate.

13. In paragraph 9, A lithium metal battery, wherein the electrolyte comprises a gel-polymer electrolyte.

14. In paragraph 13, Further comprising a separator between the cathode and the anode, The above separator is impregnated into the gel-polymer electrolyte, A lithium metal battery, wherein the gel-polymer electrolyte is filled in the pores of the separator.

15. In paragraph 9, A lithium metal battery, wherein the electrolyte comprises an argyrodite-type solid electrolyte.

16. A cathode comprising a cathode current collector, an oxide layer and a polymer coating layer; A cathode comprising a cathode current collector and a cathode active material layer; and Including an electrolyte between the cathode and the anode, The above negative electrode current collector comprises titanium or an alloy thereof, A lithium metal battery, wherein the oxide layer comprises crystalline titanium oxide.

17. In paragraph 16, A lithium metal battery, wherein the polymer coating layer comprises a polymer having a TFSI (trifluoromethanesulfonimide) functional group.

18. In paragraph 16, The above crystalline titanium oxide is a negative electrode for a lithium metal battery having an anatase phase, a rutile phase, or a combination thereof.

19. In paragraph 16, A lithium metal battery, wherein the electrolyte comprises a gel-polymer electrolyte.

20. In paragraph 19, Further comprising a separator between the cathode and the anode, The above separator is impregnated into the gel-polymer electrolyte, A lithium metal battery, wherein the gel-polymer electrolyte is filled in the pores of the separator.

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