Negative electrode for lithium secondary battery, secondary battery comprising same, and method for producing same

Abstract

Disclosed is a negative electrode for a lithium secondary battery, the negative electrode comprising: a lithium metal layer; a first protective layer disposed on the lithium metal layer and comprising a compound represented by chemical formula 1; and a second protective layer disposed on the first protective layer and comprising lithium-containing metal oxide, wherein the thickness of the first protective layer is 0.1 nm-1 µm (chemical formula 1 is as described in the description of the invention).

Description

Anode for a lithium secondary battery, a secondary battery including the same, and a method for manufacturing the same

[0001] It's about secondary batteries.

[0002]

[0003] The recent rapid proliferation of battery-powered electronic devices, such as mobile phones, laptops, and electric vehicles, has led to a rapid increase in demand for high-energy density and high-capacity secondary batteries. Accordingly, active research and development is underway to improve the performance of secondary batteries. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0004]

[0005] The present invention provides an anode for a lithium secondary battery in which dendrite formation is suppressed and lithium metal is uniformly deposited to improve the overvoltage phenomenon, and a method for manufacturing the same.

[0006]

[0007] According to one embodiment, a negative electrode for a secondary battery may include: a lithium metal layer; a first protective layer disposed on the lithium metal layer and including a compound represented by the following chemical formula 1; and a second protective layer disposed on the first protective layer and including a lithium-containing metal oxide. The thickness of the first protective layer may be 0.1 nm to 1 μm.

[0008] [Chemical Formula 1]

[0009] Li-X

[0010] In the above chemical formula 1, X is a halogen element.

[0011] According to another embodiment, a lithium secondary battery may include: a cathode layer; a lithium metal layer; a cathode layer including a first protective layer on the lithium metal layer and a second protective layer on the first protective layer; and an electrolyte layer disposed between the cathode layer and the cathode layer.

[0012] The above first protective layer may include a compound represented by the following chemical formula 1.

[0013] The second protective layer may include a lithium-containing metal oxide.

[0014] The thickness of the first protective layer may be 0.1 nm to 1 μm.

[0015] [Chemical Formula 1]

[0016] Li-X

[0017] In the above chemical formula 1, X may be a halogen element.

[0018] A method for manufacturing a negative electrode for a lithium secondary battery according to another embodiment may include: preparing a deposition solution by dissolving a compound represented by the following chemical formula 3 in an organic solvent; providing the deposition solution and lithium metal inside a reaction chamber; and reacting Li on the surface of the lithium metal with the compound volatilized from the deposition solution.

[0019] [Chemical Formula 3]

[0020] R1-X

[0021] In the above chemical formula 3,

[0022] R1 may each independently be hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0023] X may be a halogen element.

[0024]

[0025] According to one embodiment, a negative electrode for a lithium secondary battery can provide a lithium secondary battery in which lithium dendrite formation is suppressed and lithium metal is uniformly deposited, thereby improving the overvoltage phenomenon.

[0026]

[0027] FIG. 1 is a cross-sectional view of a lithium secondary battery according to one embodiment of the invention.

[0028] FIG. 2 is a cross-sectional view of a negative electrode for a lithium secondary battery according to one embodiment of the embodiment.

[0029] Fig. 3 is an enlarged cross-sectional view of area A of the negative electrode for a lithium secondary battery of Fig. 2.

[0030] Fig. 4 is an enlarged cross-sectional view of area B of the negative electrode for a lithium secondary battery of Fig. 2.

[0031] FIG. 5 is a cross-sectional view of a lithium secondary battery according to another embodiment of the invention.

[0032] Figure 6 is a plan view of a lithium secondary battery according to another embodiment of the embodiment.

[0033] Figure 7 is a cross-sectional view of a lithium secondary battery according to another embodiment of the embodiment.

[0034] Figure 8 is a conceptual diagram illustrating a method for manufacturing a negative electrode for a lithium secondary battery according to another embodiment of the present invention.

[0035] Figure 9 is a conceptual diagram illustrating an enlarged view of area C of Figure 8.

[0036] Figure 10 is a conceptual diagram illustrating an enlarged view of area C of Figure 8.

[0037] Figure 11 is an XPS graph for analyzing the surface of a negative electrode for a lithium secondary battery manufactured according to Example 1.

[0038] Figure 12 is an XPS graph for analyzing the surface of a negative electrode for a lithium secondary battery manufactured according to Example 2.

[0039] Figure 13 is an XPS graph for analyzing the surface of a negative electrode for a lithium secondary battery manufactured according to Comparative Example 2.

[0040]

[0041] 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.

[0042] 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.

[0043] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0044] 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.

[0045] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0046] 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.

[0047] Hereinafter, with reference to drawings and the like, a negative electrode for a secondary battery, a secondary battery including the same, and a manufacturing method thereof according to an implementation example are described.

[0048]

[0049] Fig. 1 is a cross-sectional view of a lithium secondary battery (10) according to an embodiment. Fig. 2 is a cross-sectional view of a negative electrode (200, hereinafter referred to as a negative electrode layer) for a lithium secondary battery according to an embodiment. Figs. 3 and 4 are cross-sectional views illustrating enlarged portions of a negative electrode layer (200, see Fig. 2) according to an embodiment. Fig. 3 illustrates an enlarged view of area A of Fig. 2.

[0050] Referring to FIG. 1, a lithium secondary battery (10) according to one embodiment may include a positive electrode layer (100), a negative electrode layer (200), and an electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). The positive electrode layer (100) may include a positive electrode current collector (110) and a positive electrode active material layer (120) on the positive electrode current collector (110). Referring to FIGS. 1 and 2, the negative electrode layer (200) may include a negative electrode current collector (210), a lithium metal layer (220) on the negative electrode current collector (210), a first protective layer (230) on the lithium metal layer (220), and a second protective layer (240) on the first protective layer (230).

[0051] However, without being limited thereto, the lithium secondary battery (10) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the electrolyte layer (300) or between the negative electrode layer (200) and the electrolyte layer (300).

[0052] (bipolar layer)

[0053] According to one embodiment, a cathode layer (100) may include a cathode current collector (110) and a cathode active material layer (120) on the cathode current collector (110). The cathode active material layer (120) may include a cathode active material, a conductive material, and a binder.

[0054] The cathode current collector (110) can provide a reference surface on which the cathode active material layer (120) is arranged. The cathode current collector (110) can include a plate or foil including, 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.

[0055] Meanwhile, unlike that illustrated in FIG. 1, in one embodiment, the positive electrode collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode collector (110) and the positive electrode active material layer (120).

[0056] A cathode active material is a material that can reversibly absorb and desorb lithium ions. The cathode active material may include, but is not necessarily limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. The cathode active materials may be used alone or as a mixture of two or more.

[0057] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c(0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mr b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Ni 1-b-c Mr b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Ni b Co c Mr d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li aMn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-f A compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0058] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z O2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 리튬 이차 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0059] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method of forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method of forming the coating layer includes, for example, spray coating, dipping, etc.

[0060] When the cathode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the lithium secondary battery (10) can be increased, thereby reducing metal dissolution of the cathode active material in a charged state. As a result, the cycle characteristics of the secondary lithium secondary battery (10) in a charged state are improved. Meanwhile, the “cycle characteristics” are characteristics indicating the degree to which the lithium secondary battery (10) is deteriorated due to charge / discharge of the lithium secondary battery (10). A lithium secondary battery (10) having high cycle characteristics may have a small degree of deterioration of the lithium secondary battery (10) due to charge / discharge, and a lithium secondary battery (10) having low cycle characteristics may have a large degree of deterioration of the lithium secondary battery (10) due to charge / discharge.

[0061] The shape of the cathode active material may include particle shapes such as a sphere or an ellipsoid, for example. The particle size and content of the cathode active material are not particularly limited.

[0062] The positive electrode active material layer (120) may include an electrolyte. The electrolyte of the positive electrode active material layer (120) may include a liquid electrolyte, a solid electrolyte, or a combination thereof.

[0063] When the positive electrode active material layer (120) includes a solid electrolyte, the solid electrolyte of the positive electrode active material layer (120) may have a particle shape. The solid electrolyte may be dispersed between the positive electrode active materials. 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 x It may include at least one selected from (0≤x≤2).

[0064] 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 It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0065] Sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0066] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When 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.

[0067] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller median particle size (D50) than the solid electrolyte included in the electrolyte layer (300). For example, the median particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) 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 median particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0068] The cathode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the lithium secondary battery (10), thereby increasing the conductivity of the cathode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0069] The positive electrode active material layer (120) may further include a binder. The binder may include a material for binding the positive electrode active material, solid electrolyte, and conductive material included in the positive electrode active material layer (120) and improving bonding strength with the positive electrode current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0070] Based on 100 parts by weight of the total of the positive electrode active material, electrolyte, conductive material, and binder, the positive electrode active material layer (120) may include 85 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, electrolyte, conductive material, and binder, the positive electrode active material layer (120) may include 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0071] Based on 100 parts by weight of the electrolyte, the positive electrode active material layer (120) may include 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive electrode active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of the electrolyte, the proportion of the conductive material may decrease, thereby lowering the electrical conductivity of the positive electrode active material layer (120). If the conductive material is included in the positive electrode active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of the electrolyte, the proportion of the conductive material may be excessively high, and thus a coating layer covering the surface of the electrolyte may not be properly formed.

[0072] The cathode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the cathode active material, electrolyte, conductive agent, and binder described above.

[0073] The electrolyte layer (300) may be disposed between the anode layer (100) and the cathode layer (200). The electrolyte layer (300) may include a liquid electrolyte, a solid electrolyte, or a combination thereof.

[0074] (electrolyte layer)

[0075] When the electrolyte layer (300) includes a liquid electrolyte, the liquid electrolyte (hereinafter referred to as the electrolyte solution) may include a non-aqueous organic solvent and a lithium salt.

[0076] Non-aqueous organic solvents can serve as a medium through which ions involved in the electrochemical reactions of a battery can move.

[0077] The non-aqueous organic solvent may be a carbonate, ester, ether, ketone, or alcohol solvent, an aprotic solvent, or a combination thereof.

[0078] Examples of carbonate solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0079] Ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone.

[0080] Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran.

[0081] Examples of ketone solvents that can be used include cyclohexanone. Examples of alcohol solvents that can be used include ethyl alcohol, isopropyl alcohol, etc., and examples of aprotic solvents that can be used include nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0082] Non-aqueous organic solvents can be used alone or in combination of two or more.

[0083] When using a carbonate solvent, a cyclic carbonate and a chain carbonate can be mixed and used, and the cyclic carbonate and the chain carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0084] Lithium salts are substances that dissolve in organic solvents and act as a source of lithium ions in the battery, enabling the basic operation of secondary batteries and promoting the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB), lithium bis(oxalato)borate (LiBOB).

[0085] When the electrolyte layer (300) includes a liquid electrolyte, a separator (not shown) may be present between the positive electrode layer (100) and the negative electrode layer (200). As such a separator (not shown), a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these may be used, and 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 be used.

[0086] A separator (not shown) 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.

[0087] 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.

[0088] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0089] 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.

[0090] 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.

[0091] When the electrolyte layer (300) includes a liquid electrolyte, the positive electrode layer (100), the negative electrode layer (200), and the separator (not shown) may be impregnated with the electrolyte.

[0092] When the electrolyte layer (300) includes a solid electrolyte, it may include a sulfide-based solid electrolyte.

[0093] A sulfide-based solid electrolyte can be manufactured by treating starting materials such as Li2S and P2S5 by a melting rapid cooling method or a mechanical milling method, for example. In addition, a heat treatment can be performed after the treatment. The solid electrolyte can be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte can be, for example, a material containing sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte can be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form a solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0094] 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 xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0095] Sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0096] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When 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 is, for example, 15 GPa to 35 GPa.

[0097] Referring to FIG. 5, when the electrolyte layer (300) includes a solid electrolyte according to one embodiment, the electrolyte layer (300) may include a first solid electrolyte layer (310) adjacent to the positive electrode layer (100) and having a first thickness (TK1) and a second solid electrolyte layer (320) adjacent to the negative electrode layer (200) and having a second thickness (TK2).

[0098] According to one embodiment, the first thickness (TK1) may be equal to or greater than the second thickness (TK2).

[0099] Referring to FIGS. 6 and 7, in another embodiment, when the electrolyte layer (300) includes a solid electrolyte, in one embodiment, the electrolyte layer (300) may include a first solid electrolyte layer (310) adjacent to the positive electrode layer (100) and having a first width (WI1) and a second solid electrolyte layer adjacent to the negative electrode layer (200) and having a second width (WI2).

[0100] According to one embodiment, the second width (WI2) may be equal to or greater than the first width (WI1).

[0101] When the electrolyte layer (300) includes a solid electrolyte, the electrolyte layer (300) may further include a binder. The binder included in the electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120).

[0102] (cathode layer)

[0103] Referring to FIGS. 1 and 2, a negative electrode layer (200) according to one embodiment may include a negative electrode collector (210). The negative electrode collector (210) may provide a reference surface on which a lithium metal layer (220) is disposed. The negative electrode collector (210) may include, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound with lithium. The material constituting the negative electrode collector (210) may include, but is not necessarily limited to, copper (Cu), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that can be used as an electrode collector may be used. The thickness of the negative electrode collector (210) may be 1 to 20 μm, for example, 5 to 15 μm, for example, 7 to 10 μm. The negative electrode collector (210) is, for example, in the form of a plate or foil. Meanwhile, in one embodiment, the negative electrode collector (210) may be omitted.

[0104] The negative electrode current collector (210) includes, for example, a first metal substrate. The first metal substrate includes, as a main component, a first metal, or is made of the first metal. The content of the first metal included in the first metal substrate is, for example, 90 wt% or more, 95 wt% or more, 99 wt% or more, or 99.9 wt% or more, based on the total weight of the first metal substrate. The first metal substrate may be made of, for example, a material that does not react with lithium, i.e., does not form an alloy and / or compound with lithium.

[0105] The first metal may be, for example, copper (Cu), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited thereto, and any metal that can be used as a current collector in the relevant technical field may be used. The first metal substrate may be composed of, for example, one of the above-described metals, or may be composed of an alloy of two or more metals. The first metal substrate may be, for example, in the form of a sheet or foil.

[0106] The cathode current collector (210) may further include a coating layer (not shown) containing a second metal on the first metal substrate.

[0107] The negative electrode current collector (210) may include, for example, a first metal substrate and a coating layer disposed on the first metal substrate and including a second metal. The second metal has a higher Mohs hardness than the first metal. That is, since the coating layer including the second metal is harder than the substrate including the first metal, deterioration of the first metal substrate can be prevented. The Mohs hardness of the material constituting the first metal substrate is, for example, 5.5 or less. The Mohs hardness of the first metal is, for example, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or less. The Mohs hardness of the first metal may be, for example, 2.0 to 6.0. The coating layer includes the second metal. The coating layer includes, for example, the second metal as a main component or is made of the second metal. The content of the second metal included in the coating layer is, for example, 90 wt% or more, 95 wt% or more, 99 wt% or more, or 99.9 wt% or more based on the total weight of the coating layer. The coating layer may be composed of, for example, a material that does not react with lithium, i.e., does not form an alloy and / or compound with lithium. The Mohs hardness of the material constituting the coating layer is, for example, 6.0 or more. For example, the Mohs hardness of the second metal is 6.0 or more, 6.5 or more, 7.0 or more, 7.5 or more, 8.0 or more, 8.5 or more, or 9.0 or more. The Mohs hardness of the second metal may be, for example, 6.0 to 12. If the Mohs hardness of the second metal is excessively low, it may be difficult to suppress deterioration of the negative electrode current collector (210). If the Mohs hardness of the second metal is excessively high, processing may not be easy. The second metal is, for example, one or more selected from titanium (Ti), manganese (Mn), niobium (Nb), tantalum (Ta), iridium (Ir), vanadium (V), rhenium (Re), osmium (Os), tungsten (W), chromium (Cr), boron (B), ruthenium (Ru), and rhodium (Rh).The coating layer may be composed of, for example, one of the above-described metals, or may be composed of an alloy of two or more metals. The difference in Mohs hardness between the first metal included in the first metal substrate and the second metal included in the coating layer may be, for example, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more. Since the first metal and the second metal have such a difference in Mohs hardness, deterioration of the negative electrode current collector (210) can be more effectively suppressed. The coating layer may have a single-layer structure or a multi-layer structure of two or more layers. The coating layer may have a two-layer structure including, for example, a first coating layer and a second coating layer. The coating layer may have a three-layer structure including, for example, a first coating layer, a second coating layer, and a third coating layer. The thickness of the coating layer may be, for example, 10 nm to 1 ㎛, 50 nm to 500 nm, 50 nm to 200 nm, or 50 nm to 150 nm. If the thickness of the coating layer is too thin, it may be difficult to suppress the uneven growth of the lithium-containing metal layer. As the thickness of the coating layer increases, the cycle characteristics of the lithium secondary battery (10) improve, but if the thickness of the coating layer is too thick, the energy density of the lithium secondary battery (10) decreases and the formation of the coating layer may not be easy. The coating layer may be formed on the first metal substrate by, for example, a vacuum deposition method, a sputtering method, a plating method, etc., but is not necessarily limited to these methods, and any method capable of forming a coating layer in the relevant technical field may be used.

[0108] For example, the negative electrode current collector (210) may have a reduced thickness compared to the negative electrode current collector included in a conventional negative electrode. Therefore, the negative electrode according to the present disclosure is distinguished from a conventional electrode including a thick film current collector, for example, by including a thin film current collector. By employing a thin film current collector having a reduced thickness in the electrode according to one embodiment, the thickness of the lithium metal layer (220) in the negative electrode including the thin film current collector may be relatively increased. As a result, the energy density of a lithium battery employing such an electrode is increased.

[0109] The negative electrode current collector (210) may have a form selected from, for example, a sheet, a foil, a film, a plate, a porous body, a mesoporous body, a body containing through holes, a polygonal ring body, a mesh body, a foam body, and a non-woven body, but is not necessarily limited to these forms, and any form used in the relevant technical field is possible.

[0110] The negative electrode current collector (210) may include, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. The negative electrode current collector (210) includes a substrate, and the substrate may have a structure including, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. An intermediate layer may additionally be disposed on the metal substrate layer.

[0111] For example, the base film may include a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. Since the base film includes a thermoplastic polymer, the base film can melt when a short circuit occurs, thereby suppressing a sudden increase in current. The base film may be, for example, an insulator. The metal substrate layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The metal substrate layer may act as an electrochemical fuse, which may be cut in the event of an overcurrent, thereby preventing a short circuit. The limit current and maximum current can be controlled by controlling the thickness of the metal substrate layer. The metal substrate layer may be plated or deposited on the base film. When the thickness of the metal substrate layer becomes thinner, the limit current and / or maximum current of the negative electrode current collector (210) decreases, so that the stability of the lithium secondary battery (10) in the event of a short circuit can be improved. A lead tab may be added on the metal substrate layer for connection to the outside. The lead tab may be welded to the metal substrate layer or the metal substrate layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or the metal substrate layer may be melted, so that the metal substrate layer may be electrically connected to the lead tab. In order to make the welding of the metal substrate layer and the lead tab more solid, a metal chip may be added between the metal substrate layer and the lead tab. The metal chip may be a thin piece of the same material as the metal of the metal substrate layer. The metal chip may be, for example, a metal foil, a metal mesh, etc.The metal piece may be, for example, aluminum foil, copper foil, SUS foil, etc. After arranging the metal piece on the metal substrate layer, the lead tab may be welded to the metal piece / metal substrate layer laminate or the metal piece / metal substrate layer / base film laminate by welding the metal piece with the lead tab. During welding, the base film, the metal layer, and / or the metal piece may melt, so that the metal layer or the metal layer / metal piece laminate may be electrically connected to the lead tab. A metal chip and / or a lead tab may be added to a portion of the metal substrate layer. The base film may have a thickness of, for example, 1 to 50 ㎛, 1.5 to 50 ㎛, 1.5 to 40 ㎛, or 1 to 30 ㎛. When the base film has a thickness in this range, the weight of the negative electrode assembly can be more effectively reduced. The melting point of the base film may be, for example, 100 to 300°C, 100 to 250°C or less, or 100 to 200°C. Since the base film has a melting point within this range, the base film can be easily bonded to the lead tab during the welding process of the lead tab by melting. To improve the adhesion between the base film and the metal substrate layer, a surface treatment such as corona treatment may be performed on the base film. The thickness of the metal substrate layer may be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. Since the metal substrate layer has a thickness within this range, conductivity can be maintained while ensuring the stability of the negative electrode. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. Since the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be performed more easily. By having this structure, the negative electrode collector (210) can reduce the weight of the electrode and consequently improve the energy density.

[0112] Referring to FIGS. 1 and 2, an anode layer (220) according to one embodiment may include a lithium metal layer (220) disposed on one or both sides of an anode current collector (210). The lithium metal layer (220) may provide a reference surface on which lithium metal is deposited by charging. The lithium metal layer (220) may include, for example, a material that reacts with lithium, i.e., forms an alloy or compound with lithium. For example, the lithium metal layer (220) may include lithium metal or a lithium alloy. For example, a lithium alloy is an alloy of lithium and another metal that can be alloyed with lithium, such as a lithium-silver alloy, a lithium-zinc alloy, a lithium-magnesium alloy, a lithium-tin alloy, etc., but is not necessarily limited thereto, and any material that forms an alloy or compound with lithium is possible. The thickness of the lithium metal layer (220) may be, for example, 50 μm or less, 35 μm or less, 1 μm to 35 μm, 1 μm to 30 μm, 5 μm to 30 μm, 10 μm to 35 μm, or 10 μm to 30 μm. When the lithium metal layer (220) has a thickness in this range, the energy density of the secondary battery can be further improved.

[0113] The thickness of the lithium metal layer (220) may be the average thickness of the lithium metal layer (220). The thickness of the lithium metal layer (220) may be the maximum thickness of the lithium metal layer (220).

[0114] The thickness of the lithium metal layer (220) can change by the lithium metal being plated by charging after the negative electrode layer (200) is introduced into the secondary battery together with the positive electrode and the electrolyte. According to one embodiment, the thickness of the lithium metal layer (220) at maximum charging can be, for example, 100 μm or less, 50 μm or less, 1 μm to 50 μm, 1 μm to 40 μm, 5 μm to 30 μm, 10 μm to 35 μm, or 10 μm to 30 μm. When the lithium metal layer (220) has a thickness in this range, the energy density of the secondary battery can be further improved.

[0115] According to one embodiment, the lithium metal layer (220) may be disposed on the negative electrode current collector (210) during the process of manufacturing the lithium secondary battery (10). The lithium metal layer (220) may be disposed on the negative electrode current collector (210) in a dry manner, for example, by deposition such as CVD or PVD. The lithium metal layer (220) may be disposed on the negative electrode current collector (210) in a wet manner, for example, by spin coating or dip coating. In addition, a method for forming the lithium metal layer (220) on the negative electrode current collector (210) may include a method of directly coating lithium metal on the negative electrode current collector (210), a method of coating lithium metal on top of a separate support, drying it, and then laminating the resulting film on the current collector, but any method that forms the lithium metal layer (220) on the negative electrode current collector (210) may be used.

[0116] According to another embodiment, the lithium metal layer (220) is free during the process of manufacturing the secondary battery (10), but when the secondary battery (10) is charged, the lithium metal layer (220) may be formed as lithium metal or a lithium alloy is deposited on the negative electrode current collector (210).

[0117] According to one embodiment, the lithium metal layer (220) may include a spherical lithium metal or a spherical lithium alloy. For example, during the charging process of a lithium ion battery, lithium ions are induced to be deposited on the lithium metal layer (220), and the spherical lithium metal or lithium alloy may be deposited on the lithium metal layer (220). Accordingly, the lithium metal layer (220) may include a spherical lithium metal or lithium alloy.

[0118] According to one embodiment, the average particle diameter (D50) of the spherical lithium metal or lithium alloy may be 0.1 to 15 μm, 0.1 to 12 μm, 0.1 to 10 μm, 1 to 15 μm, 2 to 15 μm, 3 to 15 μm, or 3 to 10 μm.

[0119] Referring to FIGS. 1 and 2, the cathode layer (220) according to one embodiment may include a first protective layer (230) disposed on one or both sides of the lithium metal layer (220).

[0120] Referring to FIG. 3, the first protective layer (230) may include a compound represented by the following chemical formula 1.

[0121] [Chemical Formula 1]

[0122] Li-X

[0123] In the above chemical formula 1, X may be a halogen element.

[0124] In one embodiment, X may be Cl or Br.

[0125] The negative electrode layer (200) includes a first protective layer (230) containing a compound represented by the above chemical formula 1, thereby preventing lithium dendrites from being formed on the surface of the lithium metal layer (220) and inducing uniform deposition of lithium metal on the lithium metal layer (220) during charging. In addition, the first protective layer (230) prevents the lithium metal layer (220) from being exposed to moisture or the air, thereby preventing the second protective layer (240) containing a lithium-containing metal oxide described below from becoming thicker than a certain thickness, thereby improving the life characteristics of the lithium secondary battery (10).

[0126] The first protective layer (230) can be formed to have a uniform thickness using a room temperature deposition process described later. The thickness (TK) of the first protective layer (230) according to the embodiment x ) may be 0.1 nm to 1 ㎛. The thickness (TK) of the first protective layer (230) x ) may be, for example, 500 nm or less, 400 nm or less, 300 nm or less, or 200 nm or less. The thickness (TK) of the first protective layer (230) X ) can be, for example, 1 nm or more, 10 nm or more, or 100 nm or more.

[0127] The thickness (TK) of the first protective layer (230) x ) may be the average thickness of the first protective layer (230). The thickness (TK) of the first protective layer (230) x ) may be the maximum thickness of the first protective layer (230).

[0128] Referring to FIG. 3, the first protective layer (230) according to one embodiment may further include a compound represented by the following chemical formula 2.

[0129] [Chemical Formula 2]

[0130] R1-Li

[0131] In the above chemical formula 2, R1 may each independently be hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0132] Referring to FIG. 3, the first protective layer (230) according to one embodiment may include at least one of methyllithium, ethyllithium, propyllithium, butyllithium, pentyllithium, or hexyllithium.

[0133] Referring to FIG. 3, according to one embodiment, the first protective layer (230) may include butyllithium.

[0134] Referring to FIGS. 1 and 2, the cathode layer (220) according to one embodiment may include a second protective layer (240) disposed on one or both sides of the first protective layer (230).

[0135] Referring to FIG. 4, the second protective layer (240) may include a lithium-containing metal oxide. The lithium-containing metal oxide may include at least one of Li2CO3, Li2O, LiOH, and Li3N. Lithium metal has a high reactivity with electrolyte components or gases present in the atmosphere, and thus may form a film such as the second protective layer (240) through a spontaneous reaction. When such a film exists below a certain thickness, it has the effect of increasing the chemical stability of the negative electrode layer (200) and increasing the mechanical strength, thereby preventing the formation of dendrites. However, when the battery is repeatedly charged and discharged, the film components may increase, depleting the electrolyte or acting as a resistive layer to reduce ionic conductivity. In addition, there is a problem that lithium is unevenly precipitated and energy density is reduced due to a film that is thicker than a certain thickness.

[0136] In the negative electrode layer (200) according to the embodiment, a second protective layer (240) is formed on a lithium metal layer (220) during the process of manufacturing a lithium secondary battery (10), and a first protective layer (230) is formed between the lithium metal layer (220) and the second protective layer (240) in a room temperature deposition manner, so that the second protective layer (240) can be maintained at a certain thickness or less even when repeated charging and discharging is performed. The thickness of the second protective layer (240) according to the embodiment may be 500 nm or less. For example, the thickness of the second protective layer (240) may be 100 nm or less, 50 nm or less, or 10 nm or less. The thickness of the second protective layer (240) according to the embodiment may be 0.1 nm or more, or 1 nm or more.

[0137] The thickness of the second protective layer (240) may be the average thickness of the second protective layer (240). The thickness of the second protective layer (240) may be the maximum thickness of the second protective layer (240).

[0138] Referring to FIG. 4, the second protective layer (240) may further include a compound represented by the following chemical formula 2.

[0139] [Chemical Formula 2]

[0140] R1-Li

[0141] In the above chemical formula 2, R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0142] Referring to FIG. 4, the second protective layer (240) according to one embodiment may include at least one of methyllithium, ethyllithium, propyllithium, butyllithium, pentyllithium, or hexyllithium.

[0143] Referring to FIG. 4, according to one embodiment, the second protective layer (240) may include butyllithium.

[0144] Referring to FIGS. 8 and 9, according to one implementation example, the second protective layer (240) may cover the entire surface of the first protective layer (230) or a portion of the surface.

[0145] Hereinafter, a method for manufacturing a negative electrode for a lithium secondary battery according to an embodiment will be specifically described.

[0146] Referring to FIG. 8, a method for manufacturing a negative electrode for a lithium secondary battery according to another embodiment may include: dissolving a compound represented by the following chemical formula 3 in an organic solvent to manufacture a deposition solution (SOL); providing the deposition solution (SOL) and lithium metal inside a reaction chamber (RCB); and reacting Li on the surface of the lithium metal with the compound volatilized from the deposition solution (SOL).

[0147] [Chemical Formula 3]

[0148] R1-X

[0149] In the above chemical formula 3,

[0150] R1 may each independently be hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0151] In one embodiment, X may be a halogen element. In one embodiment, X may be Cl or Br.

[0152] According to one embodiment, the organic solvent is Bromomethane, Chloromethane, Fluoromethane, Bromoethane, Chloroethane, Fluoroethane, Bromopropane, Chloropropane, Fluoropropane, Bromobutane, Chlorobutane, Fluorobutane, Bromopentane, Chloropentane, Fluoropentane, Bromohexane, Chlorohexane, Fluorohexane, Bromoheptane, Chloroheptane, Fluoroheptane, Bromooctane (Bromooctane), chlorooctane, fluorooctane, isopropyl bromide, isopropyl chloride, isopropyl fluoride, isobutyl bromide, isobutyl chloride, isobutyl fluoride, tert-Butyl bromide, tert-Butyl chloride, tert-Butyl fluoride.

[0153] A lithium secondary battery including a negative electrode manufactured by this method can provide improved cycle characteristics.

[0154] (deposition solution)

[0155] A deposition solution according to one embodiment can be prepared by dissolving an alkyl halide in an organic solvent.

[0156] According to one embodiment, the organic solvent may include at least one of NMP (N-methylpyrrolidone), 1,2-dimethoxyethane, dioxane, THF (Tetrahydrofuran), pentane, hexane, heptane, and octane. Such organic solvents have high reactivity and are useful for dissolving alkyl halides, and have low boiling points and thus are easy to evaporate, thereby facilitating room temperature deposition reactions.

[0157] An alkyl halide according to one embodiment may include a compound represented by chemical formula 3.

[0158] [Chemical Formula 3]

[0159] R1-X

[0160] In the above chemical formula 3,

[0161] R1 may each independently be hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0162] In one embodiment, X may be a halogen element. In one embodiment, X may be Cl or Br.

[0163] According to one embodiment, the alkyl halide is selected from the group consisting of Bromomethane, Chloromethane, Fluoromethane, Bromoethane, Chloroethane, Fluoroethane, Bromopropane, Chloropropane, Fluoropropane, Bromobutane, Chlorobutane, Fluorobutane, Bromopentane, Chloropentane, Fluoropentane, Bromohexane, Chlorohexane, Fluorohexane, Bromoheptane, Chloroheptane, Fluoroheptane, It may include at least one of Bromooctane, Chlorooctane, Fluorooctane, Isopropyl bromide, Isopropyl chloride, Isopropyl fluoride, Isobutyl bromide, Isobutyl chloride, Isobutyl fluoride, Tert-Butyl bromide, Tert-Butyl chloride, Tert-Butyl fluoride.

[0164] A deposition solution (SOL) according to one embodiment can be prepared by dissolving the compound described above in the organic solvent described above in an amount of 1 wt% to 50 wt%.

[0165] (lithium metal)

[0166] In one embodiment, the lithium metal provided within the reaction chamber may comprise lithium metal or a lithium alloy. For example, the lithium alloy may be an alloy of lithium and another metal capable of alloying with lithium, such as a lithium-silver alloy, a lithium-zinc alloy, a lithium-magnesium alloy, or a lithium-tin alloy.

[0167] Although not shown, in one embodiment, one side of the lithium metal provided within the reaction chamber may include a negative electrode current collector. In another embodiment, one side of the lithium metal provided within the reaction chamber may not include a negative electrode current collector. Since the description of the negative electrode current collector (210) described above can be applied as is, a detailed description thereof will be omitted.

[0168] Referring to FIG. 8, in one embodiment, a second protective layer including a lithium-containing metal oxide may be included on one surface of the lithium metal provided inside the reaction chamber. The second protective layer may be described in the same manner as the second protective layer (240) described above, so a detailed description thereof will be omitted. In one embodiment, the second protective layer (240) may cover the entirety or a portion of the surface of the lithium metal provided inside the reaction chamber. In one embodiment, the lithium metal layer (220) may include an area covered by the second protective layer (240) and an area not covered.

[0169] Referring to FIG. 8, a deposition solution and lithium metal may be provided inside a reaction chamber. The deposition solution may be volatilized inside the reaction chamber. Referring to FIG. 9, Li on the surface of the lithium metal may react with a compound volatilized from the deposition solution. In one embodiment, the reaction may be initiated on the surface of the lithium metal layer (220) that is not covered by the second protective layer (240). In one embodiment, the reaction may also occur on the surface of the lithium metal layer (220) that is covered by the second protective layer (240).

[0170] The reaction product may include a compound represented by the following chemical formula 1.

[0171] [Chemical Formula 1]

[0172] Li-X

[0173] In the above chemical formula 1, X may be a halogen element.

[0174] In one embodiment, X may be Cl or Br.

[0175] In one embodiment, the compound represented by the above chemical formula 1 may be lithium chloride (LiCl) or lithium bromide (LiBr).

[0176] The reaction product may include a compound represented by the following chemical formula 2.

[0177] [Chemical Formula 2]

[0178] R1-Li

[0179] In the above chemical formula 2, R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0180] In one embodiment, the compound represented by the above formula 2 may include at least one of Methyllithium, Ethyllithium, Propyllithium, Butyllithium, Pentylithium, or Hexyllithium.

[0181] In one embodiment, the compound represented by the above chemical formula 2 may include butyllithium.

[0182] In one embodiment, before providing the deposition solution and lithium metal into the reaction chamber, the interior of the chamber may be maintained in a vacuum. The reaction of Li on the surface of the lithium metal with the compound volatilized from the deposition solution may be performed in a vacuum.

[0183] In one embodiment, the interior of the reaction chamber may contain an inert gas. For example, it may contain at least one of Nitrogen, Argon, Helium, Neon, Krypton, and Xenon.

[0184] In one embodiment, the reaction temperature of the compound volatilized from the deposition solution and Li on the lithium metal surface may be 0°C to 100°C. For example, the reaction temperature may be 0°C to 75°C, the reaction temperature may be 0°C to 50°C, and the reaction temperature may be 0°C to 30°C.

[0185] In one embodiment, the reaction time of Li on the lithium metal surface and the compound volatilized from the deposition solution may be from 1 second (sec) to 600 seconds (sec). The reaction time of the compound may be from 10 seconds (sec) to 600 seconds (sec).

[0186] In one embodiment, referring to FIG. 9, Li on the lithium metal surface and a compound volatilized from the deposition solution may initiate a reaction on the lithium metal surface not covered by the second protective layer (240). Since the above description can be applied to the reaction product, a detailed description thereof will be omitted.

[0187] Referring to FIGS. 9 and 10, a reaction initiated on a lithium metal surface occurs across the entire lithium metal surface, and after a sufficient amount of time has elapsed, a first protective layer (230) having a uniform thickness below a certain thickness may be formed. Since the above-described description can be applied to the reaction product as is, a detailed description thereof will be omitted.

[0188] The cathode manufactured in this way can improve the life characteristics of a secondary battery by including a protective layer that suppresses the growth of lithium dendrites on the lithium metal layer.

[0189] The negative electrode manufactured in this way forms a protective layer between the lithium metal and the oxide film, thereby preventing the oxide film from thickening beyond a certain thickness during the charging process, thereby preventing an increase in the surface resistance of the lithium metal.

[0190]

[0191] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0192]

[0193] Example 1

[0194] A deposition solution containing bromobutane dissolved in THF (Tetrahydrofuran) and lithium metal having an oxide film formed on the surface with a thickness of 20 μm was prepared in an area of ​​10 cm x 10 cm and placed in a reaction chamber saturated with argon (Ar) gas to carry out the reaction between bromobutane and lithium metal by room temperature deposition. The lithium metal was placed in the reaction chamber in a state of being adhered to copper foil.

[0195] The internal temperature of the reaction chamber was maintained at 27°C, and after 30 seconds, the lithium metal was removed to complete the formation of the halogen protective layer. The thickness of the halogen protective layer thus formed was 200 nm.

[0196] A pouch cell was manufactured by using a lithium foil with a thickness of 20 μm as a counter electrode, placing a polypropylene separator (Celgard 3510) between the counter electrode and the cathode, and injecting an electrolyte.

[0197] As an electrolyte, a solution containing 1.15 M LiPF6 dissolved in EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (2:4:4 volume ratio) was used.

[0198]

[0199] Example 2

[0200] A pouch cell was manufactured in the same manner as in Example 1, except that chlorobutane was dissolved in THF (Tetrahydrofuran) as a deposition solution.

[0201]

[0202] Comparative Example 1

[0203] A pouch cell was manufactured in the same manner as Example 1, except that a 20 μm thick lithium metal was laminated on a copper foil without a deposition reaction, as a negative electrode for a lithium secondary battery.

[0204]

[0205] Comparative Example 2

[0206] A coating solution containing lithium chloride (LiCl) dispersed at a concentration of 10 wt% in the organic solvent THF (Tetrahydrofuran) was applied to a 200 nm thickness on the surface of a 20 μm thick lithium metal using a bar coater. After application, the solution was dried at room temperature for 1 hour to complete the formation of a halogen protective layer on the surface of the lithium metal. A pouch cell was manufactured using the same method as Example 1, except for the method of forming the halogen protective layer.

[0207]

[0208] Evaluation Example 1: Surface Analysis of Anode for Lithium Secondary Battery

[0209] The results of surface analysis of the negative electrodes for lithium secondary batteries manufactured in Examples 1 to 2 and Comparative Example 2 through XPS analysis are shown in FIGS. 11 to 12.

[0210] Referring to Fig. 11, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Example 1 did not exhibit a Br peak on the surface, but a Li peak did. That is, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Example 1 had a lithium oxide film on the surface of the halogen protective layer.

[0211] Referring to Fig. 12, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Example 2 did not show a Cl peak on the surface, but a Li peak appeared. That is, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Example 2 had a lithium oxide film on the surface of the halogen protective layer.

[0212] On the other hand, referring to Fig. 13, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Comparative Example 2 had a Cl peak appearing on the surface. That is, it was confirmed that the negative electrode for a lithium secondary battery manufactured in Comparative Example 2 had a halogen protective layer (LiCl) formed on the outermost surface of the negative electrode layer.

[0213]

[0214] Evaluation Example 2: Analysis of Overvoltage Data for Lithium Secondary Battery

[0215] In order to compare the resistance characteristics of lithium metals manufactured through examples and comparative examples, lithium|lithium symmetrical cells were manufactured and the initial overvoltage was measured. The symmetrical cells were manufactured by punching out the lithium metals manufactured through each example and comparative example into circles with a diameter of 11 mm, placing a PE separator (20 um) between the lithium and lithium, placing them inside a coin cell, and injecting 40 uL of 1M LiPF6 EC / DEC (50 / 50 vol%) electrolyte, and then manufacturing the cells at a current of 1 mA / cm. 2 The measurement was made by repeating charge and discharge for 1 hour at a current of . Table 1 shows the initial overvoltage data according to Examples 1 and 2 and Comparative Examples 1 and 2.

[0216]

[0217] Initial overvoltage (mV) Example 194 Example 2100 Comparative Example 1470 Comparative Example 2210

[0218]

[0219] synthesis

[0220] Referring to Figures 11 to 13, it was confirmed that in Examples 1 and 2, a halogen protective layer was formed between the lithium metal layer and the lithium oxide film, but in Comparative Example 2, the halogen protective layer was located at the outermost layer of the cathode layer.

[0221] Referring to Table 1, it can be confirmed that in Comparative Examples 1 and 2, a larger overvoltage occurs during discharge than in Examples 1 and 2, and this is particularly evident at the end of the discharge.

[0222]

[0223] 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 patent 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

lithium metal layer; A first protective layer disposed on the lithium metal layer and comprising a compound represented by the following chemical formula 1; and A second protective layer disposed on the first protective layer and comprising a lithium-containing metal oxide; The thickness of the first protective layer is 0.1 nm to 1 ㎛, the negative electrode for a lithium secondary battery: [Chemical Formula 1] Li-X In the above chemical formula 1, X is a halogen element. In the first paragraph, The above X is a negative electrode for a lithium secondary battery, wherein Cl or Br. In the first paragraph, The first protective layer further comprises a compound represented by the following chemical formula 2, wherein the negative electrode for a lithium secondary battery: [Chemical Formula 2] R1-Li In the above chemical formula 2, R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group. In the third paragraph, A negative electrode for a lithium secondary battery, wherein the first protective layer comprises at least one of methyllithium, ethyllithium, propyllithium, butyllithium, pentyllithium, or hexyllithium. In the first paragraph, A negative electrode for a lithium secondary battery, wherein the thickness of the second protective layer is 0.1 nm to 500 nm. In the first paragraph, The lithium-containing metal oxide is a negative electrode for a lithium secondary battery, comprising at least one of Li2CO3, Li2O, LiOH, and Li3N. In the first paragraph, The second protective layer further comprises a compound represented by the following chemical formula 2, wherein the negative electrode for a lithium secondary battery: [Chemical Formula 2] R1-Li R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group. In the first paragraph, A negative electrode for a lithium secondary battery, wherein the second protective layer comprises at least one of methyllithium, ethyllithium, propyllithium, butyllithium, pentyllithium, or hexyllithium. In the first paragraph, The second protective layer is a negative electrode for a lithium secondary battery that covers the entirety or part of the surface of the first protective layer. bipolar layer; A cathode layer comprising a lithium metal layer, a first protective layer on the lithium metal layer, and a second protective layer on the first protective layer; and It includes an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The first protective layer comprises a compound represented by the following chemical formula 1, The second protective layer comprises a lithium-containing metal oxide, A lithium secondary battery wherein the thickness of the first protective layer is 0.1 nm to 1 μm: [Chemical Formula 1] Li-X In the above chemical formula 1, X is a halogen element. In Article 10, A lithium secondary battery wherein the above X is Cl or Br. In Article 10, The first protective layer further comprises a compound represented by the following chemical formula 2, wherein the lithium secondary battery: [Chemical Formula 2] R1-Li In the above chemical formula 2, R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group. In Article 10, A lithium secondary battery wherein the electrolyte layer includes a liquid electrolyte, a solid electrolyte, or a combination thereof. In Article 13, The electrolyte layer comprises a first solid electrolyte layer adjacent to the positive electrode layer and having a first width; and A second solid electrolyte layer adjacent to the cathode layer and having a second width; A lithium secondary battery, wherein the second width is greater than the first width. Preparing a deposition solution by dissolving a compound represented by the following chemical formula 3 in an organic solvent; Providing the deposition solution and lithium metal inside the reaction chamber; and A method for manufacturing a negative electrode for a lithium secondary battery, comprising reacting Li on the surface of the lithium metal with the compound volatilized from the deposition solution: [Chemical Formula 3] R1-X In the above chemical formula 3, R1 is each independently hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group, X is a halogen element. In Article 15, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the organic solvent comprises at least one of NMP (N-methylpyrrolidone), 1,2-dimethoxyethane, dioxane, and THF (Tetrahydrofuran). In Article 15, A method for manufacturing a negative electrode for a lithium secondary battery, wherein reacting Li on the surface of the lithium metal with the compound volatilized from the deposition solution is performed inside a reaction chamber containing an inert gas. In Article 15, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the reaction temperature of Li on the surface of the lithium metal and the compound volatilized from the deposition solution is 0°C to 100°C. In Article 15, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the reaction time of Li on the surface of the lithium metal and the compound volatilized from the deposition solution is 1 second (sec) to 600 seconds (sec). In paragraph 15, A method for manufacturing a negative electrode for a lithium secondary battery, wherein lithium metal provided inside a reaction chamber includes a second protective layer including a lithium-containing metal oxide.

Images