Positive electrode for all-solid-state battery, all-solid-state battery containing the same, and method for manufacturing a positive electrode for all-solid-state battery

Abstract

The present invention provides a positive electrode for an all-solid-state battery with excellent electrical properties and improved atmospheric stability, as well as an all-solid-state battery containing the same. [Solution] The present invention relates to a positive electrode for an all-solid-state battery, an all-solid-state battery containing the same, and a method for manufacturing a positive electrode for an all-solid-state battery, comprising a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a binder, and an additive, and the additive comprises metal acetylacetonate.

Description

[Technical Field]

[0001] This invention relates to a positive electrode for an all-solid-state battery, an all-solid-state battery containing the same, and a method for manufacturing the positive electrode for an all-solid-state battery. [Background technology]

[0002] Recently, industrial demands have led to active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in the fields of information-related equipment and communication equipment, but also in the automotive sector. In the automotive sector, safety is especially important because it is related to human life.

[0003] Recently, all-solid-state batteries have been proposed that replace the electrolyte with a solid electrolyte. By not using a flammable organic dispersion medium, all-solid-state batteries can significantly reduce the possibility of fire or explosion even if a short circuit occurs. Therefore, such all-solid-state batteries can be made much safer than lithium-ion batteries that use an electrolyte. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Korean Registered Patent Publication No. 10-2622757 [Overview of the project] [Problems that the invention aims to solve]

[0005] The problem that this invention aims to solve is to provide a positive electrode for an all-solid-state battery with excellent electrical properties and improved atmospheric stability, and an all-solid-state battery containing the same.

[0006] Another problem that the present invention aims to solve is to provide a method for manufacturing a positive electrode for an all-solid-state battery that has excellent electrical properties and improved atmospheric stability. [Means for solving the problem]

[0007] The positive electrode for an all-solid-state battery according to the concept of the present invention comprises a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a binder, and an additive, the additive may include metal acetylacetonate.

[0008] An all-solid-state battery according to the concept of the present invention may include a positive electrode, a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode.

[0009] A method for manufacturing a positive electrode for an all-solid-state battery according to the concept of the present invention comprises preparing a positive electrode current collector, mixing a positive electrode active material, a sulfide-based solid electrolyte, a binder, an additive, and a solvent to form a positive electrode active material slurry, and coating the positive electrode current collector with the positive electrode active material slurry, wherein the additive may include metal acetylacetonate. [Effects of the Invention]

[0010] The positive electrode for all-solid-state batteries according to the present invention can have excellent electrical properties and excellent atmospheric stability. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view of an all-solid-state battery according to an embodiment of the present invention. [Figure 2A] This is a cross-sectional view along the line A-A' in Figure 1. [Figure 2B] This is a cross-sectional view along the line B-B' in Figure 1. [Figure 3] This is an enlarged cross-sectional view of region M in Figure 2A, illustrating the positive electrode active material layer 120 according to an embodiment of the present invention. [Figure 4] This is an enlarged cross-sectional view of region M in Figure 2A, illustrating the positive electrode active material layer 120 according to a comparative example of the present invention. [Figure 5]This is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the positive electrode active material layer 120 according to a comparative example of the present invention. [Figure 6] This is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the positive electrode active material layer 120 according to an embodiment of the present invention. [Figure 7] This is a cross-sectional view along the line A-A' in Figure 1, illustrating an all-solid-state battery according to another embodiment of the present invention. [Figure 8] This graph shows the measurement results of the shear viscosity of the positive electrode active material slurry of Example 1 of the present invention. [Figure 9] This graph shows the results of measuring the shear viscosity of the positive electrode active material slurry in Example 2 of the present invention. [Figure 10] This graph shows the results of measuring the shear viscosity of the positive electrode active material slurry in Example 3 of the present invention. [Figure 11] This graph shows the results of measuring the shear viscosity of a comparative example of the present invention's positive electrode active material slurry. [Figure 12A] This graph shows the XPS analysis results for the positive electrode of Example 1 of the present invention. [Figure 12B] This graph shows the XPS analysis results for the positive electrode of Example 1 of the present invention. [Figure 12C] This graph shows the XPS analysis results for the positive electrode of Example 1 of the present invention. [Figure 12D] This graph shows the XPS analysis results for the positive electrode of Example 1 of the present invention. [Figure 13A] This graph shows the XPS analysis results for the positive electrode of a comparative example of the present invention. [Figure 13B] This graph shows the XPS analysis results for the positive electrode of a comparative example of the present invention. [Figure 13C] This graph shows the XPS analysis results for the positive electrode of a comparative example of the present invention. [Figure 13D] This graph shows the XPS analysis results for the positive electrode of a comparative example of the present invention. [Modes for carrying out the invention]

[0012] To fully understand the structure and effects of the present invention, preferred embodiments will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in various forms and modified in many ways. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those who are ordinary skill in the art of which the invention pertains.

[0013] In this specification, when a given component is referred to as being on another component, it means that it can be formed directly on the other component or that a third component can be interposed between them. Furthermore, in the drawings, the thickness of components is exaggerated for the sake of efficient illustration of the technical content. Parts indicated by the same reference number throughout the specification refer to the same component.

[0014] The embodiments described herein are explained with reference to cross-sectional and / or plan views, which are ideal illustrative diagrams of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the efficient explanation of the technical content. Therefore, the regions illustrated in the drawings have schematic attributes, and the shapes of the regions illustrated in the drawings are for illustrative purposes only of the specific shape of the region of the element and are not intended to limit the scope of the invention. In the various embodiments herein, terms such as first, second, third, etc., have been used to describe various components, but these components should not be limited by such terms. These terms are used merely to distinguish certain components from others. The embodiments described and illustrated herein also include complementary embodiments.

[0015] The terms used herein are for illustrative purposes only and are not intended to limit the invention. In this specification, the singular form includes the plural form unless otherwise specified. The secondary battery configurations referred to as “comprises” and / or “comprising” in this specification do not preclude the presence or addition of one or more other components.

[0016] In this specification, “these combinations” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the constituents.

[0017] In this specification, each of the following phrases may include any one or all possible combinations of the items listed together with the phrase in question: “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B, or C,” “at least one of A, B, and C,” and “at least one of A, B, or C.”

[0018] Unless otherwise defined herein, particle size may refer to average particle size. Furthermore, particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. Average particle size (D50) can be measured by methods widely known to those skilled in the art, such as using a particle size analyzer, or by using a transmission electron microscope or scanning electron microscope. Alternatively, it can be measured using a dynamic light-scattering device, and the average particle size (D50) value can be calculated after data analysis and counting the number of particles for each particle size range. Alternatively, it can be measured using the laser diffraction method. When measuring using the laser diffraction method, more specifically, the particles to be measured are dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size analyzer (for example, Microtrac MT 3000), and after irradiating with ultrasound at approximately 28 kHz at an output of 60 W, the average particle size (D50) based on the 50% particle size distribution in the analyzer can be calculated.

[0019] In one embodiment, the average particle size as used herein may mean the diameter measured by arbitrarily selecting about 100 particles from an electron microscope image. Alternatively, the average particle size as used herein may mean the diameter of a particle that can be measured with a particle size analyzer and whose cumulative volume in the particle size distribution is 50% by volume.

[0020] Figure 1 is a plan view of an all-solid-state battery according to an embodiment of the present invention. Figure 2A is a cross-sectional view taken along the line A-A' in Figure 1. Figure 2B is a cross-sectional view taken along the line B-B' in Figure 1.

[0021] Referring to Figures 1, 2A, and 2B, the unit cell CEL of the all-solid-state battery according to the present invention may include a positive electrode layer 100, a negative electrode layer 200 facing the positive electrode layer 100, and a solid electrolyte layer 300 disposed between the positive electrode layer 100 and the negative electrode layer 200. However, it is not limited thereto, and the unit cell CEL may further include additional functional layers, such as adhesion-enhancing layers, disposed between the positive electrode layer 100 and the solid electrolyte layer 300 or between the negative electrode layer 200 and the solid electrolyte layer 300.

[0022] Positive electrode layer 100 The positive electrode layer 100 according to one embodiment of the present invention may include a positive electrode current collector 110 and a positive electrode active material layer 120 disposed on the positive electrode current collector 110.

[0023] The positive electrode current collector 110 can provide a reference surface on which the positive electrode active material layer 120 is placed. The positive electrode current collector 110 may include a plate or foil containing, 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 alloys thereof.

[0024] On the other hand, unlike the one shown in Figure 1, the positive electrode current collector 110 can be omitted in one embodiment of the present invention. Although not shown, a carbon layer with a thickness of 0.1 μm to 4 μm may be further arranged between the positive electrode current collector 110 and the positive electrode active material layer 120 to increase the bonding force between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0025] Positive electrode active material layer 120 Figure 3 illustrates the positive electrode active material layer 120 according to an embodiment of the present invention, and is an enlarged cross-sectional view of region M in Figure 2A.

[0026] Referring to Figure 3, the positive electrode active material layer according to an embodiment of the present invention may include a positive electrode active material CAM, a sulfide-based solid electrolyte SSE, a binder BND, and an additive ADT.

[0027] The cathode active material CAM of the cathode active material layer 120 can include a material that can reversibly absorb and desorb lithium ions. The cathode active material CAM can include a plurality of particles. The cathode active material CAM can include, for example, 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, lithium iron phosphate, etc., nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, etc., but is not necessarily limited thereto. The cathode active materials CAM can each be alone or a mixture of two or more kinds.

[0028] The lithium transition metal oxide is, for example, Li 2-α , α , c 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), Lia Nor 1-b-c Mn b B c D α (0.90≦a≦1、0≦b≦0.5、0≦c≦0.05、0<α≦2)、Li a Nor 1-b-c Mn 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 Nor b E c G d O2(0.90≦a≦1、0≦b≦0.9、0≦c≦0.5、0.001≦d≦0.1)、Li a Nor b Co c Mn 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 a Mn2GbO4(0.90≦a≦1、0.001≦b≦0.1),QO2、QS2、LiQS2、V2O5、LiV2O5、LiIO2、LiVO4、Li 3-f J2(PO4)3(0≦f≦2)、Li 3-fThis compound is represented by one of the following: Fe2(PO4)3 (0≦f≦2) or LiFePO4. In such a compound, 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, rare earth elements, 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" may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0029] The positive electrode active material CAM may include, for example, lithium salts of transition metal oxides having a layered rock salt type structure among the lithium transition metal oxides mentioned above. "Layered rock salt type structure" refers to, for example, a cubic rock salt type structure. <111> This structure consists of alternating, regular arrangements of oxygen and metal atomic layers in a directional pattern, where each atomic layer forms a two-dimensional plane. The "cubic rock salt type structure" is a type of crystalline structure, specifically a sodium chloride type (NaCl type) structure, where the face-centered cubic lattices (fcc) formed by the cations and anions are offset from each other by approximately half the ridge length of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zIt can be a ternary lithium transition metal oxide such as O2(NCM)(0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). When the positive electrode active material CAM contains a ternary lithium transition metal oxide having a layered rock salt structure, the energy density of the unit cell CEL increases, and the thermal stability can be improved.

[0030] The above-described compound contained in the positive electrode active material CAM can be covered by a coating layer (not shown). The positive electrode active material can also be used as a mixture of the above-described compound and the compound with the coating layer added. On the other hand, the coating layer added to the surface of the positive electrode active material can contain, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compound forming such a coating layer is amorphous or crystalline. The coating elements contained in the coating layer can include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating layer can contain, for example, Li2O-ZrO2 (LZO), etc. The coating layer forming method is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating layer forming method is, for example, spray coating, dipping method, etc.

[0031] When the positive electrode active material CAM contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, it is possible to increase the capacity density of the unit cell CEL and reduce the metal elution of the positive electrode active material in the charged state. As a result, the cycle characteristics of the unit cell CEL in the charged state are improved. On the other hand, "cycle characteristics" means a characteristic indicating the degree to which the unit cell CEL deteriorates by charging / discharging of the unit cell CEL. A unit cell CEL with high cycle characteristics has a small degree of deterioration of the unit cell CEL by charging / discharging, and a unit cell CEL with low cycle characteristics can have a large degree of deterioration of the unit cell CEL by charging / discharging.

[0032] The positive electrode active material CAM can have a particle shape such as a sphere, ellipsoid, etc. The particle size and content of the positive electrode active material are not particularly limited.

[0033] The solid electrolyte SSE in the positive electrode active material layer 120 may have a particle shape. The solid electrolyte SSE may be dispersed between the positive electrode active material CAM. The solid electrolyte SSE may include sulfide-based solid electrolytes with excellent lithium ion conductivity characteristics. Examples of sulfide-based solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX (where 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, and Li2S-P2S5-Z. m S n (m and n are positive numbers, uppercase "Z" is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, the uppercase letter "M" is one of P, Si, Ge, B, Al, or Gain), Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), or Li 7-x PS 6-x I x It must contain at least one value within the range (0 ≤ x ≤ 2).

[0034] 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), or Li 7-x PS 6-x I xThe compound may be an argyrodite-type compound containing at least one of (0 ≤ x ≤ 2). In particular, sulfide-based solid electrolytes may be argyrodite-type compounds containing at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I.

[0035] Alternatively, a sulfide-based solid electrolyte is Li 7-a-c M a PS 6-c X c The compound may be an argyrodite-type compound containing (0≦a≦2, 0≦c≦2). Here, X may be F, Br, Cl, I, or a combination thereof. M may be scandium (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 It may be um (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.

[0036] The density of the argyrodite-type solid electrolyte can be 1.5 g / cc to 2.0 g / cc. Having a density of 1.5 g / cc or higher for the argyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, preventing defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the solid electrolyte can be, for example, 15 GPa to 35 GPa.

[0037] The solid electrolyte SSE in the positive electrode active material layer 120 may have a smaller average particle size than the first and second solid electrolytes in the solid electrolyte layer 300, which will be described later. For example, the average particle size of the solid electrolyte SSE 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 average particle size of the solid electrolyte in the solid electrolyte layer 300. On the other hand, the average particle size may be the median diameter measured using a laser particle size analyzer.

[0038] The binder BND within the positive electrode active material layer 120 can bond the positive electrode active material CAM and the solid electrolyte SSE within the positive electrode active material layer 120 to each other. The binder BND may contain a substance to improve the bonding force between the positive electrode active material layer 120 and the positive electrode current collector 110.

[0039] The binder BND may include, for example, at least one of polyvinylidene fluoride, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate. In one embodiment, the binder BND may include polyvinylidene fluoride.

[0040] The additive ADT in the positive electrode active material layer 120 can improve the dispersibility of the positive electrode active material CAM, solid electrolyte SSE, and binder BND within the positive electrode active material layer 120. Therefore, the additive ADT can improve the electrical properties of the positive electrode.

[0041] The additive ADT may include, for example, a metal acetylacetonate. The central metal of the metal acetylacetonate is not particularly limited as long as it is a metal that can form a complex compound with the acetylacetonate ligand. For example, the central metal of the metal acetylacetonate may include at least one of aluminum (Al), manganese (Mn), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zirconium (Zr), tin (Sn), zinc (Zn), chromium (Cr), or a combination thereof. Specifically, the central metal may include Al(III), Cu(II), Mn(II), Mn(III), Fe(III), Zr(IV), Sn(II), Sn(IV), Cr(III), etc. In one embodiment, the central metal of the metal acetylacetonate may be an aluminum cation (Al 3+ ) is possible.

[0042] When the central metal of a metal-acetylacetonate is a divalent cation, two acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and consequently, the metal-acetylacetonate can have a four-coordinate plane square structure.

[0043] When the central metal of a metal-acetylacetonate is a trivalent cation, three acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and consequently, the metal-acetylacetonate can have a hexa-coordinate octahedron structure.

[0044] When the central metal of a metal-acetylacetonate is a tetravalent cation, four acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and as a result, the metal-acetylacetonate can have an octahedron with an eight-coordinate biscape (bisphenoid geometry), or a distorted square arrangement, etc.

[0045] Metal-acetylacetonates include, but are not limited to, aluminum(III) acetylacetonate, copper(II) acetylacetonate, manganese(II) acetylacetonate, and manganese(III) acetylacetonate. Additive ADT can interact with sulfide-based solid electrolytes SSE. For example, Lewis acid-base interactions, ion-ion interactions, or ion-dipole interactions can act between the additive ADT and the sulfide-based solid electrolyte SSE.

[0046] For example, the metal ions of metal acetylacetonate act as Lewis acids, and the sulfur ions (S) of sulfide-based solid electrolytes SSEs 2- ) may act as a Lewis base, and a Lewis acid-base interaction may occur between the additive ADT and the sulfide-based solid electrolyte SSE. Alternatively, the sulfur anion (S) of the sulfide-based solid electrolyte SSE may act as a Lewis base. 2- ) or lithium cation (Li + An ion-ion interaction may occur between the metal ions of the metal acetylacetonate and the metal ions of the metal acetylacetonate. Alternatively, since all metal ions of metal acetylacetonate and acetylacetone ligands are polar, the sulfur anion (S) of the sulfide-based solid electrolyte SSE may interact with the metal acetylacetonate ligand. 2- ) or lithium cation (Li + ) and ion dipole interactions are also possible.

[0047] The additive ADT can interact with the binder BND. For example, forces such as Lewis acid-base interactions, ion-dipole interactions, and van der Waals forces can act between the additive ADT and the binder BND.

[0048] For example, the metal ions of metal acetylacetonate may act as Lewis acids, and the functional groups contained in the binder BND (e.g., carbonyl groups (C=O), hydroxyl groups (-OH), epoxy groups (-O-), etc.) may act as Lewis bases, resulting in Lewis acid-base interactions between the additive ADT and the binder BND. Alternatively, van der Waals forces may act between the acetylacetone ligand of the metal acetylacetonate and the nonpolar portion of the binder (e.g., the fluorocarbon chain of PVDF).

[0049] The additive ADT interacts with at least one of the sulfide-based solid electrolyte SSE and binder BND to prevent aggregation of the solid electrolyte SSE and binder BND. Suppressing aggregation of the solid electrolyte SSE and binder BND improves the phase stability of the positive electrode active material slurry and enhances the electrical properties of the positive electrode.

[0050] In a cathode active material slurry, the solid electrolyte SSE and binder BND can aggregate due to electrostatic attraction, van der Waals forces, and interactions with the solvent. When the solid electrolyte SSE and binder BND aggregate, they cannot be uniformly dispersed in the solvent and may form clusters. These aggregated clusters reduce the contact area with the solvent, which can decrease the particle dispersibility in the slurry. The aggregated clusters can also cause non-uniformity in the viscosity and rheological properties of the slurry, reducing its flowability and thus decreasing the phase stability of the slurry.

[0051] As described above, the additive ADT according to embodiments of the present invention can interact with at least one of the sulfide-based solid electrolyte SSE and the binder BND. The additive ADT can be located on the surface of the sulfide-based solid electrolyte SSE to prevent aggregation of the binder BND and the solid electrolyte. Alternatively, the additive ADT can be located around the binder BND to prevent aggregation of the binder BND and the solid electrolyte. In other words, the additive ADT according to embodiments of the present invention can interact with at least one of the sulfide-based solid electrolyte SSE and the binder BND to prevent aggregation of the binder BND and the solid electrolyte SSE. Consequently, the additive BND can improve the dispersibility and phase stability of the positive electrode active material slurry, thereby improving the electrical properties of the positive electrode produced.

[0052] Figure 4 illustrates the positive electrode active material layer 120 according to a comparative example of the present invention, and is an enlarged cross-sectional view of region M in Figure 2A. Figure 5 is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the positive electrode active material layer 120 according to a comparative example of the present invention.

[0053] Referring to Figures 4 and 5, in the comparative example of the positive electrode active material layer 120, the solid electrolyte SSE and binder BND can exist in an aggregated clump state. If the solid electrolyte SSE and binder BND aggregate and a large amount of electrically insulated binder BND is distributed around the solid electrolyte SSE, contact between the solid electrolyte particles SSE or between the solid electrolyte SSE and the positive electrode active material CAM can be prevented. If contact between the solid electrolyte particles SSE or between the solid electrolyte SSE and the positive electrode active material CAM is prevented, the lithium ion migration pathway and the electron conduction pathway may be blocked, potentially reducing the ionic and electronic conductivity of the positive electrode 100.

[0054] Figure 6 is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the positive electrode active material layer 120 according to an embodiment of the present invention. Referring to Figures 3 and 6, the solid electrolyte SSE and binder BND can exist in a uniformly dispersed form without agglomerating in the positive electrode active material layer 120 according to the embodiment.

[0055] Reducing the distribution of binder BND around the solid electrolyte SSE increases the contact area between the solid electrolyte SSE and the positive electrode active material CAM, thereby improving lithium-ion conductivity. Furthermore, reducing factors that hinder electron flow improves the electron conduction pathway, further enhancing electronic conductivity.

[0056] The additive ADT can improve the atmospheric stability of the positive electrode active material slurry and the positive electrode active material layer 110. The positive electrode active material slurry and the positive electrode active material layer 110 for all-solid-state batteries contain a sulfide-based solid electrolyte SSE that is highly reactive with water (H2O) and carbon dioxide (CO2), and therefore have relatively low atmospheric stability.

[0057] When a chemically stable metal acetylacetonate is located around a sulfide-based solid electrolyte (SSE), contact between the SSE and moisture in the air can be limited. Alternatively, the metal acetylacetonate can adsorb water molecules on the surface of the SSE, or its ligand structure can suppress the reaction with moisture, thereby mitigating the reaction of the SSE with moisture. Consequently, the metal acetylacetonate can suppress the reaction of the SSE with moisture in the air, thereby improving the atmospheric stability of the positive electrode active material slurry and the positive electrode active material layer 110.

[0058] The additive ADT protects sulfide-based solid electrolytes (SSEs) from atmospheric moisture through Lewis acid-base interactions, etc., while having little effect on the chemical structure of the sulfide-based solid electrolytes (SSEs). In other words, the additive ADT can improve the atmospheric stability of sulfide-based solid electrolytes (SSEs) without deforming them.

[0059] The additive ADT in the manufactured positive electrode can be confirmed through FT-IR spectroscopy (Fourier-Transform Infrared Spectroscopy), TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis, or GC-MS (Gas Chromatography-Mass Spectrometry).

[0060] As one embodiment, a sample taken from the positive electrode active material layer 120 is analyzed by FT-IR to detect the additive ADT by a method of confirming a characteristic peak (e.g., C=O stretching vibration in the range of 1600~1500 cm -1 region) of the acetylacetonate ligand. As other embodiments, metal ions and acetylacetonate ligands can be individually detected from the positive electrode surface through TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis to directly or indirectly confirm the presence of metal acetylacetonate.

[0061] The content of the additive ADT in the positive electrode active material layer 120 can be from 0.01 part by weight to 0.8 part by weight based on 100 parts by weight of the positive electrode active material layer 120. For example, the content of the additive ADT can be from 0.03 part by weight to 0.5 part by weight, or from 0.05 part by weight to 0.3 part by weight.

[0062] If the content of the additive ADT in the positive electrode active material layer 120 is too small, it may be difficult to improve the air stability of the positive electrode active material layer 120. If the content of the additive ADT in the positive electrode active material layer 120 is too large, a capacity reduction of the positive electrode 100 may occur. When the content of the additive ADT satisfies the above range, the positive electrode 100 can have improved air stability along with excellent capacity.

[0063] The weight ratio of additive ADT to binder BND in the positive electrode active material layer 120 may be 1:0.01 to 1:0.5. For example, the weight ratio of additive ADT to binder BND may be 1:0.02 to 1:0.3 or 1:0.03 to 1:0.2. If the weight ratio of additive ADT to binder BND satisfies the above range, the positive electrode 100 can have electrical conductivity and ionic conductivity.

[0064] The sulfide-based solid electrolyte SSE in the positive electrode active material layer 120 may be present in an amount of 5 to 30 parts by weight per 100 parts by weight of the positive electrode active material layer 120. For example, the content of the sulfide-based solid electrolyte SSE may be 5 to 25 parts by weight or 10 to 25 parts by weight.

[0065] The positive electrode active material layer 120 may further contain a conductive material. The conductive material may have conductivity without causing a chemical change in the unit cell CEL and enhance the conductivity of the positive electrode active material and solid electrolyte. The conductive material may include carbon-based materials. The conductive material may include at least one of, for example, graphite, carbon black, acetylene black, carbon nanofibers, or carbon nanotubes.

[0066] When based on 100 parts by weight of the solid electrolyte SSE, the positive electrode active material layer 120 may contain 1 to 50 parts by weight of conductive material. If the amount of conductive material in the positive electrode active material layer 120 is less than 1 part by weight when based on 100 parts by weight of the solid electrolyte, the proportion of conductive material decreases, which may reduce the electrical conductivity of the positive electrode active material layer 120. If the amount of conductive material in the positive electrode active material layer 120 is more than 50 parts by weight when based on 100 parts by weight of the solid electrolyte SSE, the proportion of conductive material is excessively high, which may prevent the coating layer covering the surface of the solid electrolyte SSE from being properly formed.

[0067] In addition to the positive electrode active material CAM, solid electrolyte SSE, binder BND, additive ADT, and conductive material described above, the positive electrode active material layer 120 may further contain additives such as fillers, coating agents, dispersants, and ion conductivity enhancers.

[0068] Positive electrode manufacturing method A method for manufacturing a positive electrode according to an embodiment of the present invention may include preparing a positive electrode current collector, mixing a positive electrode active material, a sulfide-based solid electrolyte, a binder, an additive, and a solvent to form a positive electrode active material slurry, and coating the positive electrode current collector with the positive electrode active material slurry.

[0069] As described above, the positive electrode current collector can be a plate or foil containing 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 alloys thereof.

[0070] A cathode active material slurry can be formed by mixing a cathode active material, a sulfide-based solid electrolyte, a binder, and additives in a solvent. The solvent may be a nonpolar organic solvent or a weakly polar organic solvent with low reactivity with the sulfide-based solid electrolyte. For example, the solvent may include at least one of xylene, benzene, toluene, pentane, hexane, cyclohexane, octyl acetate, or a combination thereof. In one embodiment, the solvent may include octyl acetate.

[0071] Any mixing method that is accessible to a typical technician is acceptable and is not limited to any specific method.

[0072] As an example, the mixing can be carried out using a mixer or kneader. In one embodiment of the present invention, mixing can be carried out using a PD mixer (Planetary Disperser mixer), planetary mixer, paddle mixer, ribbon mixer, dual shaft mixer mixer, high-speed impeller mixer, or propeller mixer at 20°C to 60°C for 10 to 90 minutes.

[0073] The positive electrode active material, sulfide-based solid electrolyte, binder, and additives may each be the same as those described above.

[0074] The positive electrode active material may be in powder form. The positive electrode active material may include, but is not 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 manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. Each of the positive electrode active materials CAM may be a single material or a mixture of two or more.

[0075] Sulfide-based solid electrolytes include, for example, Li 7-a-c M1 a PS 6-c X1 c(0≦a≦2, 0≦c≦2) includes, where X1 includes at least one of F, Br, Cl, I, or a combination thereof, and M1 includes scandium (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), and osmium (Os). It may include at least one of the following: 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 any combination thereof.

[0076] The additive may include, for example, a metal acetylacetonate, the central metal of which may include at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zinc (Zn), chromium (Cr), or a combination thereof.

[0077] The binder may include, for example, at least one of polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polytetrafluoroethylene, or a combination thereof.

[0078] The positive electrode active material slurry may further contain a conductive material. The conductive material may include at least one of the following: graphite, carbon black, acetylene black, carbon nanofibers, or carbon nanotubes.

[0079] In the manufactured cathode active material slurry, the additive ADT interacts with at least one of the sulfide-based solid electrolyte SSE and the binder BND to prevent aggregation of the binder BND and the solid electrolyte SSE. Consequently, the additive BND can improve the dispersibility of the cathode active material slurry and enhance phase stability. The additive ADT can also prevent the degradation of the sulfide-based solid electrolyte SSE by suppressing contact between the sulfide-based solid electrolyte SSE and moisture and solvents in the air.

[0080] On the other hand, additives can generally not affect the chemical structure of sulfide-based solid electrolytes. In other words, additives can prevent the degradation of sulfide-based solid electrolytes without deforming them.

[0081] A positive electrode active material slurry can be coated onto a positive electrode current collector and dried to form a positive electrode active material layer. The coating can be performed using conventional methods. For example, coating can be done using a bar coater, blade coater, etc. Any method capable of applying the slurry is acceptable, and the examples described are not limited.

[0082] The drying process can be carried out using a dryer. For example, the dryer may include, but is not limited to, a convection oven or a vacuum oven.

[0083] Negative electrode layer 200 The negative electrode layer 200 may include a negative electrode current collector 210 and a coating layer 220 on the negative electrode current collector 210. The negative electrode current collector 210 can provide a reference surface on which the coating layer 220 is placed. The negative electrode current collector 210 may include a material that does not react with lithium, i.e., does not form any alloys or compounds with lithium. For example, the negative electrode current collector 210 may include at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or alloys thereof. The thickness of the negative electrode current collector 210 may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0084] The negative electrode current collector 210 may be composed of one of the above-mentioned metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector 210 may have, for example, a plate shape or a foil shape. On the other hand, in one embodiment, the negative electrode current collector 210 may be omitted.

[0085] Coating layer 220 The coating layer 220 allows lithium metal to grow between the unit cell CEL and the negative electrode current collector 210 during charging. The coating layer 220 acts as a protective layer for the lithium metal while simultaneously suppressing the deposition and growth of lithium dendrites.

[0086] The coating layer 220 may contain metals and carbon. For example, the coating layer 220 may contain at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer 220 may contain at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer 220 may contain a mixture of carbon black and silver (Ag).

[0087] The coating layer 220 may further contain other additives in addition to metal and carbon. The coating layer 220 may further contain at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion conductivity enhancers.

[0088] The coating layer 220 may be less thick than the positive electrode active material layer 120. The thickness of the coating layer 220 may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 120. The thickness of the coating layer 220 may be, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the coating layer 220 is excessively thin, lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210 may cause the coating layer 220 to collapse, degrading the cycle characteristics of the all-solid-state battery. If the thickness of the coating layer 220 is excessively increased, the energy density of the all-solid-state battery will decrease, and the internal resistance of the all-solid-state battery due to the coating layer 220 will increase, degrading the cycle characteristics of the cell. On the other hand, although not shown, a carbon layer may be further included between the coating layer 220 and the solid electrolyte layer 300 to improve adhesion.

[0089] solid electrolyte layer 300 The solid electrolyte layer 300 can be provided between the positive electrode layer 100 and the negative electrode layer 200. The solid electrolyte layer 300 can include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer 300 can be derived from the solid electrolyte composite described later with reference to FIG. 4. The solid electrolyte in the solid electrolyte layer 300 can be the same as or different from any one of the substances contained in the solid electrolyte in the above-described positive electrode active material layer 120.

[0090] The solid electrolyte layer 300 can include a first solid electrolyte layer 310 and a second solid electrolyte layer 320. The first solid electrolyte layer 310 can be adjacent to the positive electrode layer 100, and the second solid electrolyte layer 320 can be adjacent to the negative electrode layer 200.

[0091] Referring to FIG. 2A, the first solid electrolyte layer 310 can include a first solid electrolyte. The first solid electrolyte can have a particle shape such as a sphere, an ellipsoid, etc. The first solid electrolyte can include a sulfide-based solid electrolyte. The first solid electrolyte can be amorphous, crystalline, or in a mixed state thereof. Also, the solid electrolyte can be, for example, one containing at least 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 material containing Li2S-P2S5 as the sulfide-based solid electrolyte material forming the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5 = 50:50 to 90:10.

[0092] As one embodiment, the first solid electrolyte is Li 7-x PS 6-x Cl x (0 ≦ x ≦ 2), Li 7-x PS 6-x Br x (0 ≦ x ≦ 2), or Li 7-x PS 6-x I xThe first solid electrolyte may include an argyrodite-type compound containing at least one of the values ​​(0 ≤ x ≤ 2). The first solid electrolyte is Li6PS5Cl, Li6PS5Br, or Li6PS 5I It may include argyrodite-type compounds containing at least one of the following:

[0093] In another embodiment, the first solid electrolyte is Li 7-a-c M a PS 6-c X c This compound may contain argyrodite-type compounds, where X may be Cl, Br, or a combination thereof; M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof; and each of a and c may be a real number between 0 and 2.

[0094] The density of the argyrodite-type solid electrolyte can be 1.5 g / cc to 2.0 g / cc. Having a density of 1.5 g / cc or higher for the argyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, preventing defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the first solid electrolyte is, for example, 15 GPa to 35 GPa.

[0095] The first solid electrolyte layer 310 may further contain a binder. The binder contained in the solid electrolyte layer 300 may be, but is not limited to, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc. The binder of the first solid electrolyte layer 310 may be the same as or different from the binder contained in the positive electrode active material layer 120 or the binder contained in the coating layer 220.

[0096] The second solid electrolyte layer 320 may contain a second solid electrolyte. The second solid electrolyte may have particle shapes such as spheres or ellipsoids.

[0097] The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same as or similar to that described earlier for the first solid electrolyte. In one embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. In another embodiment, the second solid electrolyte may have a similar composition to the first solid electrolyte.

[0098] The second solid electrolyte can come into direct contact with the coating layer 220. Therefore, the second solid electrolyte can suppress the formation of lithium dendrites between the coating layer 220 and the negative electrode current collector 210. The second solid electrolyte can effectively suppress negative electrode side reactions. Therefore, the cell performance of the all-solid-state battery according to the present invention can be improved.

[0099] The first solid electrolyte layer 310 may have a first thickness TK1, and the second solid electrolyte layer 320 may have a second thickness TK2. The first thickness TK1 and the second thickness TK2 may be the same or different. In one embodiment, the first thickness TK1 may be greater than the second thickness TK2. For example, the first thickness TK1 may be 1.1 to 5 times the second thickness TK2.

[0100] Referring again to Figures 1, 2A, and 2B, the positive electrode layer 100 and the first solid electrolyte layer 310 can constitute the positive electrode mixture layer CSH. The negative electrode layer 200 and the second solid electrolyte layer 320 can constitute the negative electrode mixture layer ASH. The positive electrode mixture layer CSH can be laminated on the negative electrode mixture layer ASH.

[0101] The areas of the negative electrode mixture layer (ASH) and the positive electrode mixture layer (CSH) can be different from each other. Specifically, the area of ​​the negative electrode mixture layer (ASH) may be larger than the area of ​​the positive electrode mixture layer (CSH). The positive electrode mixture layer (CSH) can be completely stacked on top of the negative electrode mixture layer (ASH).

[0102] In one embodiment of the present invention, the first solid electrolyte layer 310 may have substantially the same area as the positive electrode layer 100. The second solid electrolyte layer 320 may have substantially the same area as the negative electrode layer 200.

[0103] Specifically, the positive electrode mixture layer CSH may have a first width WI1 in the first direction D1. The negative electrode mixture layer ASH may have a second width WI2 in the first direction D1. The first width WI1 may be smaller than the second width WI2. The positive electrode mixture layer CSH may have a third width WI3 in the second direction D2. The negative electrode mixture layer ASH may have a fourth width WI4 in the second direction D2. The third width WI3 may be smaller than the fourth width WI4.

[0104] The unit cell CEL according to this embodiment can be manufactured by forming a negative electrode mixture layer ASH on a first carrier film, forming a positive electrode mixture layer CSH on a second carrier film, and then laminating the negative electrode mixture layer ASH and the positive electrode mixture layer CSH.

[0105] The unit cell CEL according to this embodiment may further include a gasket GSK. The gasket GSK may be provided so as to surround the positive electrode mixture layer CSH. The gasket GSK can fill the step on the side surface of the unit cell CEL caused by the area difference between the negative electrode mixture layer ASH and the positive electrode mixture layer CSH. The gasket GSK may surround all four sides of the positive electrode mixture layer CSH. As an example, the thickness of the gasket GSK may be substantially the same as or less than the thickness of the positive electrode mixture layer CSH. In one embodiment, the positive electrode current collector 110 may be provided at a higher position than the gasket GSK.

[0106] The positive electrode current collector 110 may include a positive electrode tab CTB. The positive electrode tab CTB may be a protruding region of the positive electrode current collector 110. In one embodiment, the positive electrode tab CTB may protrude in a second direction D2.

[0107] The negative electrode current collector 210 may include a negative electrode tab ATB. The negative electrode tab ATB may be a protruding region of the negative electrode current collector 210. In one embodiment, the negative electrode tab ATB may protrude in the direction opposite to the second direction D2.

[0108] In the embodiments described later, detailed explanations of technical features that overlap with those previously explained with reference to Figures 1, 2A, and 2B will be omitted, and the differences will be explained in detail.

[0109] Figure 7 illustrates an all-solid-state battery according to another embodiment of the present invention and is a cross-sectional view along the line A-A' in Figure 1. Referring to Figure 7, the negative electrode layer 200 of the unit cell CEL may further include a lithium metal layer 400 between the negative electrode current collector 210 and the coating layer 220. The thickness of the lithium metal layer 400 may further increase when the unit cell CEL is charged. The coating layer 220 acts as a protective layer for the lithium metal layer 400 and at the same time can suppress the growth of lithium dendrites from the lithium metal layer 400.

[0110] The lithium metal layer 400 may contain lithium or a lithium alloy. Since the lithium metal layer 400 is a lithium-containing metal layer, it can function, for example, as a lithium reservoir. Examples of lithium alloys include, but are not limited to, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, and Li-Si alloys; any alloy that can be used as a lithium alloy in the art may be used. The lithium metal layer 400 may be formed from one of these alloys or from lithium, but can be formed from various types of alloys. The lithium metal layer 400 may be, for example, a plated layer. The lithium metal layer 400 may be deposited between the coating layer 220 and the negative electrode current collector 210 during the charging process of a unit cell CEL, for example.

[0111] In another embodiment of the present invention, the lithium metal layer 400 within the negative electrode 200 may be provided between the negative electrode current collector 210 and the coating layer 220, for example, before the assembly of the unit cell CEL. When the lithium metal layer 400 is placed between the negative electrode current collector 210 and the coating layer 220 before the assembly of the all-solid-state battery, the lithium metal layer 400 acts as a lithium reservoir because it is a lithium-containing metal layer. For example, a lithium foil may be placed between the negative electrode current collector 210 and the coating layer 220 before the assembly of the unit cell CEL.

[0112] If the lithium metal layer 400 is deposited by charging after the assembly of the unit cell CEL, the energy density of the unit cell CEL may increase because the unit cell CEL does not contain the lithium metal layer during assembly. When the unit cell CEL is charged, it is possible to charge it beyond the charging capacity of the coating layer 220. That is, the coating layer 220 is overcharged. In the initial stages of charging, lithium may be absorbed by the coating layer 220. If the capacity of the coating layer 220 is exceeded during charging, lithium may be deposited, for example, between the negative electrode coating layer 220 and the negative electrode current collector 210. The deposited lithium may form the metal layer 400.

[0113] The lithium metal layer 400 can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer 400 can be ionized and moved to the positive electrode 100. In other words, lithium can be used as the negative electrode active material in the unit cell CEL. Furthermore, since the coating layer 220 covers the lithium metal layer 400, the coating layer 220 protects the lithium metal layer 400 while simultaneously suppressing the deposition and growth of lithium dendrites. Therefore, the coating layer 220 can suppress short circuits and capacity degradation in the unit cell CEL, thereby improving the cycle characteristics of the unit cell CEL.

[0114] If a lithium metal layer 400 is formed by charging after the assembly of the unit cell CEL, the negative electrode 200, i.e., the negative electrode current collector 210 and the coating layer 220 and the region between them, may be a lithium (Li)-free region in the initial state of the unit cell CEL or after complete discharge.

[0115] The lithium metal layer 400 may have a fifth width WI5 in the first direction D1. The fifth width WI5 may be the same as or larger than the first width WI1. The fifth width WI5 may be the same as or smaller than the second width WI2. For example, the fifth width WI5 may be larger than the first width WI1 and smaller than the second width WI2.

[0116] The negative electrode 200 may further include a thin film provided between the negative electrode current collector 210 and the coating layer 220. The thin film is provided on one surface of the negative electrode current collector 210 and can form an alloy with lithium.

[0117] The thin film may contain elements that can form alloys with lithium, for example. Elements that can form alloys with lithium include, but are not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. Any element that can form alloys with lithium in the relevant technical field can be used. The thin film may be composed of one of these metals, or of an alloy of various metals.

[0118] By arranging the thin film on one surface of the negative electrode current collector 210, the deposition morphology of the lithium metal layer deposited between the thin film and the coating layer 220 is further flattened, thereby further improving the cycle characteristics of the all-solid-state battery.

[0119] The thickness of the thin film may be, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is less than 1 nm, the function of the thin film may not be easily achieved. If the thickness of the thin film is too thick, the thin film itself may absorb lithium, reducing the amount of lithium deposited on the negative electrode 200, which can lower the energy density of the all-solid-state battery and degrade its cycle characteristics. The thin film can be formed on the negative electrode current collector 210 by, for example, vacuum deposition, sputtering, or plating, but is not limited to these methods; any method capable of forming a thin film in the relevant art can be used.

[0120] The present invention will be described in more detail below through examples. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

[0121] Example 1 (Manufacturing of positive electrode active material slurry) LiNi 0.8 Co 0.1 Al 0.1 O2(NCA) powder was used as the solid electrolyte, and argyrodite-based solid electrolyte (Li6PS5Cl) powder was prepared as the sulfide-based solid electrolyte. Vinylidene fluoride / hexafluoropropylene copolymer (PVdF / HFP) was prepared as the binder, and carbon nanofibers (CNF) were prepared as the conductive material. Aluminum acetylacetonate (Al(acac)3) was prepared as an additive.

[0122] These materials were mixed in octyl acetate solvent in a weight ratio of positive electrode active material:solid electrolyte:additive:conductive material:binder = 84.97:13:0.03:1:1 to produce a positive electrode active material slurry.

[0123] (Positive electrode manufacturing) The positive electrode was manufactured by coating an aluminum positive electrode current collector with the aforementioned positive electrode active material slurry and drying it at 130°C for 10 minutes.

[0124] (Solid electrolyte layer manufacturing) A solid electrolyte slurry was prepared by adding an argyrodite-type solid electrolyte, Li6PS5Cl, to an isobutylyl isobutylate binder solution containing a butyl acrylate polymer (the mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight). The prepared solid electrolyte slurry was coated onto a release polytetrafluoroethylene film and dried at 60°C for 2 hours to produce a solid electrolyte membrane.

[0125] (Manufacturing of all-solid-state batteries) A symmetrical coin cell was manufactured by applying the manufactured positive electrode to both the working electrode and the counter electrode in the same manner.

[0126] Example 2 The cathode active material slurry was manufactured using the same method as in Example 1, except that the mixture was weight-ratio of cathode active material:solid electrolyte:additive:conductive material:binder = 84.9:13:0.1:1:1.

[0127] Example 3 The cathode active material slurry was manufactured in the same manner as in Example 1, except that the mixture was prepared in the weight ratio of cathode active material:solid electrolyte:additive:conductive material:binder = 84.8:13:0.2:1:1.

[0128] Comparative Example The cathode active material slurry was manufactured using the same method as in Example 1, except that no additives were added during the manufacturing process, and the mixture was prepared in the weight ratio of cathode active material:solid electrolyte:conductive material:binder = 85:13:1:1.

[0129] Evaluation Example 1: Evaluation of the stability of the cathode active material slurry phase The shear viscosity was measured for the positive electrode active material slurries produced according to the examples and comparative examples using an Anton Paar Rheometer. After adding 10 ml of the positive electrode active material slurry to the apparatus, the shear viscosity was measured.

[0130] Phase stability was evaluated by measuring the shear viscosity (viscosity at a shear rate of 10¹ / s) of the positive electrode slurries of the examples and comparative examples immediately after preparation and at room temperature (20°C) after being left undisturbed for 1 day. The results are shown in Figures 8 to 11 and Table 1. The viscosity increase rate was calculated using the following formula 1. [Formula 1] Viscosity increase rate (%) = [(Shear viscosity after standing for 1 day without stirring - Shear viscosity immediately after manufacturing) / Shear viscosity immediately after manufacturing] × 100

[0131] [Table 1]

[0132] Referring to Figures 8 to 11 and Table 1, it can be confirmed that the viscosity change rate after standing without stirring is significantly smaller for the positive electrode active material slurry according to the example compared with that of the positive electrode active material slurry according to the comparative example.

[0133] Evaluation Example 2: Evaluation of positive electrode ionic conductivity and electronic conductivity The ionic and electronic conductivity of the positive electrode were evaluated using the symmetric coin cells from the examples and comparative examples in the following manner.

[0134] Electrochemical Impedance Spectroscopy (EIS) was performed on a symmetric coin cell. The EIS was conducted at an amplitude of approximately 10 mV, a frequency of 10 mHz to 1 MHz, and an air atmosphere at 45°C. The positive electrode plate is a mixed conductor capable of simultaneous electron and ion transport, allowing for the design of a corresponding equivalent circuit. After obtaining a Nyquist plot from the impedance analysis, the ionic and electronic conductivity of the positive electrode plate were separated and extracted. The results are shown in Table 2.

[0135] [Table 2]

[0136] Referring to Table 2, it can be confirmed that the positive electrode according to the example has superior ionic and electronic conductivity compared to the positive electrode according to the comparative example.

[0137] Evaluation Example 3: Solid Electrolyte Evaluation X-ray photoelectron spectroscopy (XPS) analysis was performed on the positive electrodes manufactured according to Example 1 and the Comparative Example. Subsequently, the positive electrodes of Example 1 and the Comparative Example were exposed to air for more than one day, and then XPS analysis was performed again. The results of the XPS analysis before and after exposure to air are shown in Figures 12A to 12D and Figures 13A to 13D.

[0138] Referring to Figures 13A to 13D, which are XPS analysis graphs for the positive electrode of the comparative example, it can be confirmed that the chemical structure of the solid electrolyte changed before and after exposure to air. Referring to Figures 12A to 12D, which are XPS analysis graphs for the positive electrode of Example 1, it can be confirmed that the chemical structure of the solid electrolyte remained largely unchanged before and after exposure to air.

[0139] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects. [Explanation of Symbols]

[0140] 100 Positive electrode layer 110 Positive electrode current collector 120 Cathode active material layer 200 Negative electrode layer 210 Negative electrode current collector 220 Coating layer 300 solid electrolyte layer 310 First solid electrolyte layer 320 Second solid electrolyte layer ADT additive BND Binder CAM positive electrode active material CELL Unit Cell SSE Sulfide solid electrolyte

Claims

1. A positive electrode for a solid-state battery, The positive electrode current collector and the positive electrode active material layer on the positive electrode current collector are included. The positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a binder, and an additive. The aforementioned additive includes metal acetylacetonate. Positive electrode for all-solid-state batteries.

2. The central metal of the metal-acetylacetonate includes at least one of aluminum (Al), manganese (Mn), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zirconium (Zr), tin (Sn), zinc (Zn), chromium (Cr), or a combination thereof. A positive electrode for an all-solid-state battery according to claim 1.

3. At least one of the following acts as an attractive force: between the additive and the sulfide-based solid electrolyte, or between the additive and the binder. A positive electrode for an all-solid-state battery according to claim 1.

4. The content of the additive is 0.01 to 0.8 parts by weight per 100 parts by weight of the positive electrode active material layer. A positive electrode for an all-solid-state battery according to claim 1.

5. The weight ratio of the binder to the additive is 1:0.01 to 1:0.

5. A positive electrode for an all-solid-state battery according to claim 1.

6. The content of the sulfide-based solid electrolyte is 5 to 25 parts by weight per 100 parts by weight of the positive electrode active material layer. A positive electrode for an all-solid-state battery according to claim 1.

7. The sulfide-based solid electrolyte is Li 7-x PS 6-x Cl x (0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (0 ≤ x ≤ 2), Li 7-x PS 6-x I x (0 ≤ x ≤  2), Li 7-y M1 y PS 6-z M2 z、 or includes at least one of combinations thereof, The aforementioned M1 is one or more elements selected from groups 3 to 15 of the periodic table. The aforementioned M2 is one or more elements selected from Group 17 of the periodic table. 0 ≤ x ≤ 2, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 2. A positive electrode for an all-solid-state battery according to claim 1.

8. The binder is a fluorine-based binder, a rubber-based binder, or a combination thereof. A positive electrode for an all-solid-state battery according to claim 1.

9. The binder comprises at least one of polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polytetrafluoroethylene, or a combination thereof. A positive electrode for an all-solid-state battery according to claim 1.

10. The positive electrode active material layer further contains a conductive material, The conductive material includes at least one of the following: natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, or a combination thereof. A positive electrode for an all-solid-state battery according to claim 1.

11. The positive electrode described in claim 1, The negative electrode and, A solid electrolyte layer between the positive electrode and the negative electrode is included. All-solid-state battery.

12. The solid electrolyte layer contains a sulfide-based solid electrolyte. The all-solid-state battery according to claim 11.

13. The negative electrode includes a negative electrode current collector and a coating layer on the negative electrode current collector. The coating layer comprises a carbon-based material and a metal. The all-solid-state battery according to claim 11.

14. The carbon-based material includes at least one of the following: carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, or a combination thereof. The aforementioned metal includes at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof. The all-solid-state battery according to claim 13.

15. The coating layer further comprises a binder. The all-solid-state battery according to claim 13.

16. Prepare the positive electrode current collector, The process involves mixing a positive electrode active material, a sulfide-based solid electrolyte, a binder, additives, and a solvent to form a positive electrode active material slurry. Coating the positive electrode current collector with the positive electrode active material slurry, Includes, The aforementioned additive includes metal acetylacetonate. A method for manufacturing a positive electrode for all-solid-state batteries.

17. The central metal of the metal-acetylacetonate includes at least one of aluminum (Al), manganese (Mn), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zirconium (Zr), tin (Sn), zinc (Zn), chromium (Cr), or a combination thereof. A method for manufacturing a positive electrode for an all-solid-state battery according to claim 16.

18. The weight ratio of the binder to the additive is 1:0.01 to 1:0.

5. A method for manufacturing a positive electrode for an all-solid-state battery according to claim 16.

19. The sulfide-based solid electrolyte is Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), Li 7-x PS 6-x I x (0≦x≦2), Li 7-y M1 y PS 6-z M2 z、 or including at least one of these combinations, The aforementioned M1 is one or more elements selected from groups 3 to 15 of the periodic table. The aforementioned M2 is one or more elements selected from Group 17 of the periodic table. 0 ≤ x ≤ 2, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 2. A method for manufacturing a positive electrode for an all-solid-state battery according to claim 16.

20. The binder comprises at least one of polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polytetrafluoroethylene, or a combination thereof. A method for manufacturing a positive electrode for an all-solid-state battery according to claim 16.

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