Positive electrode active material for all-solid-state battery, method for producing the same, positive electrode for all-solid-state battery including the same, and all-solid-state battery

Abstract

The present invention relates to a positive electrode active material for an all-solid-state battery, a method for producing the same, a positive electrode for an all-solid-state battery including the same, and an all-solid-state battery.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application Nos. 10-2023-0154597, 10-2023-0154618, 10-2023-0154618, and 10-2024-0144764, 10-2024-0144764, filed November 9, 2023, and all contents disclosed in the documents of these Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material for an all-solid-state battery, a method for producing the same, a positive electrode for an all-solid-state battery including the same, and an all-solid-state battery. [Background technology]

[0003] Lithium secondary batteries are widely used as power sources for portable devices, including IT mobile devices, and in recent years, the market has seen substantial growth, from small lithium secondary batteries to medium- to large-sized secondary batteries. Their use as automotive batteries in particular is on the rise. To be used as a power source for electric vehicles, lithium secondary batteries must have high energy density and high output characteristics, and ensuring safety is of particular importance.

[0004] Conventional lithium secondary batteries use a liquid non-aqueous organic electrolyte, which poses the risk of fire and explosion. In fact, explosions have occurred in products using this electrolyte, making it urgent to solve these problems.

[0005] All-solid-state batteries are batteries in which such organic electrolytes are replaced with solid electrolytes, and all of the components of the battery, such as the electrodes and electrolyte, are made of solids. Due to the high safety of the solid electrolyte itself, it is possible to fundamentally solve the risk of fire and explosion.

[0006] Candidates for the solid electrolyte of all-solid-state lithium-ion secondary batteries include gel-type polymer electrolytes, sulfide-based and oxide-based solid electrolytes, among which sulfide-based solid electrolytes have a solubility of 1×10-2 It exhibits high lithium ion conductivity of over S / cm and has a wide potential window of over 5 V, meaning that there is little degradation of its properties even in extreme environments, and it offers great advantages in designing high-energy density lithium ion secondary batteries.

[0007] All-solid-state batteries using sulfide-based solid electrolytes have a problem in which capacity is not properly expressed due to high interfacial resistance that occurs at the interface between the positive electrode active material and the sulfide-based solid electrolyte.The main causes of this interfacial resistance have been proposed to be 1) the space charge layer phenomenon, in which a lithium-deficient layer is formed at the solid electrolyte interface due to the difference in chemical potential between the positive electrode active material and the lithium ions in the solid electrolyte, and 2) the formation of an interfacial impurity layer due to a chemical reaction at the interface between the positive electrode active material and the solid electrolyte.

[0008] To solve these problems, a technology for introducing a coating layer onto the surface of a positive electrode active material has been applied, and lithium oxides such as Li-MO (where M is B, Al, Zr, P, Ti, Nb, or W) are known as coating layer materials. However, the coating layer materials known to date are still insufficient to solve the above problems, and therefore, there is a need for further development of coating layer materials that can reduce the interfacial resistance generated at the interface between the positive electrode active material and the sulfide-based solid electrolyte. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent Publication No. 2017-0070239 Summary of the Invention [Problem to be solved by the invention]

[0010] In order to solve the above problems, the present inventors have conducted extensive research and discovered that coating the surface of a lithium metal oxide cathode active material with lithium aluminum gallium fluoride, which is a compound represented by the following Chemical Formula 1, or lithium gallium fluoride, which is a compound represented by the following Chemical Formula 2, can reduce the interfacial resistance between the cathode active material and the solid electrolyte, thereby completing the present invention.

[0011] Therefore, an object of the present invention is to provide a cathode active material for an all-solid-state battery that can reduce the interfacial resistance between the cathode active material and the solid electrolyte, a method for producing the same, and a cathode including the same.

[0012] Another object of the present invention is to provide an all-solid-state battery including the positive electrode, which has excellent life characteristics and discharge capacity. [Means for solving the problem]

[0013] In order to achieve the above purpose, The present invention relates to a core comprising a lithium metal oxide; and The positive electrode active material for an all-solid-state battery includes a coating portion located on the surface of the core portion and including a compound represented by the following Chemical Formula 1 or a compound represented by the following Chemical Formula 2:

[0014] [Chemical formula 1] Li 3+x Al [1-(1 / 3)x-y] Ga y F6 wherein x is 0≦x≦0.3; wherein y is 0 <y<1であり、 (1 / 3)x+y is 0<(1 / 3)x+y<1, [Chemical formula 2] Li 3+z Ga [1-(1 / 3)z] F6 The z is in the range of −0.6≦z≦0.3.

[0015] The present invention also provides a method for preparing a mixture comprising the steps of: (1) mixing a lithium precursor, an aluminum precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide, or mixing a lithium precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture; (2) heating and drying the mixture; and (3) calcining the heated and dried mixture.

[0016] The present invention also provides a positive electrode for an all-solid-state battery, comprising the positive electrode active material of the present invention, a solid electrolyte, a conductive material, and a binder.

[0017] The present invention also provides an all-solid-state battery comprising: the positive electrode of the present invention; a negative electrode; and a solid electrolyte layer between the positive electrode and the negative electrode. [Effects of the Invention]

[0018] The cathode active material for an all-solid-state battery of the present invention includes a coating portion containing a compound represented by the following Chemical Formula 1 or a compound represented by the Chemical Formula 2 on the surface of a core portion containing lithium metal oxide as a cathode active material, thereby making it possible to suppress side reactions occurring between the cathode active material and the solid electrolyte and reduce interfacial resistance.

[0019] As a result, an all-solid-state battery including the positive electrode active material can have improved life characteristics and discharge capacity. DETAILED DESCRIPTION OF THE INVENTION

[0020] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention.

[0021] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "comprise" or "have" and the like specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0022] The present invention will now be described in more detail.

[0023] All-solid-state batteries use a solid electrolyte to conduct lithium ions, so the movement of lithium ions during charging and discharging occurs in a solid state. In other words, in all-solid-state batteries, lithium ions can only move through the actual contact points between the positive electrode and the solid electrolyte, so minimizing the interfacial resistance between the positive electrode and the solid electrolyte can improve the performance of all-solid-state batteries.

[0024] However, there is a problem in that side reactions occur at the actual contact points between the positive electrode and the solid electrolyte, which increases the interfacial resistance.

[0025] Therefore, the present invention aims to provide a positive electrode active material that can reduce the interface resistance between the positive electrode and the solid electrolyte.

[0026] Cathode active material for all-solid-state batteries The present invention relates to a core comprising a lithium metal oxide; and The positive electrode active material for an all-solid-state battery includes a coating portion located on the surface of the core portion and including a compound represented by the following Chemical Formula 1 or a compound represented by the following Chemical Formula 2:

[0027] [Chemical formula 1] Li 3+x Al [1-(1 / 3)x-y] Ga y F6 x satisfies 0 ≦ x ≦ 0.3, y satisfies 0 < y < 1, (1 / 3)x + y satisfies 0 < (1 / 3)x + y < 1, [Chemical Formula 2] Li 3+z Ga [1-(1 / 3)z] F6 z satisfies -0.6 ≦ z ≦ 0.3.

[0028] The positive electrode active material of the present invention has a core-shell structure. The core part contains a lithium metal oxide, and the coating part corresponding to the shell may contain the compound represented by the above Chemical Formula 1 or the compound represented by the above Chemical Formula 2. More specifically, the positive electrode active material of the present invention may include a core part containing a lithium metal oxide as the positive electrode active material and a coating part containing the compound represented by the above Chemical Formula 1 as the buffer layer. Or, the positive electrode active material of the present invention may include a core part containing a lithium metal oxide as the positive electrode active material and a coating part containing the compound represented by the above Chemical Formula 2 as the buffer layer.

[0029] The lithium metal oxide is a substance capable of inserting and desorbing lithium ions, and there is no particular limitation as long as it can be used as the positive electrode active material of a lithium ion secondary battery.

[0030] For example, the positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2), and a compound substituted with one or more transition metals; Chemical Formula Li x M y O2 (M is selected from the group consisting of Co, Mn, Ni, Al, Fe, V, Zn, Cr, Ti, Ta, Mg, Mo, Zr, W, Sn, Hf, Nd and Gd, x satisfies 0 < x ≦ 1.5, y satisfies 0 < y ≦ 1); Chemical Formula Li 1+x Mn 2-x O4 (0 ≦ x ≦ 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8; Chemical Formula LiNi1-x M x Ni-site lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga; 0.01≦x≦0.3); chemical formula: LiMn 2-x M x Lithium manganese composite oxides represented by O2 (M = Co, Ni, Fe, Cr, Zn, or Ta; 0.01 ≤ x ≤ 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu, or Zn); LiNi x Mn 2-x The lithium manganese composite oxide having a spinel structure represented by O4; LiCoPO4; or LiFePO4; may be included, but is not limited to these.

[0031] The coating portion may be located on the surface of the core portion and may include a compound represented by the following Chemical Formula 1 or a compound represented by the following Chemical Formula 2:

[0032] [Chemical formula 1] Li 3+x Al [1-(1 / 3)x-y] Ga y F6 wherein x is 0≦x≦0.3; wherein y is 0 <y<1であり、 (1 / 3)x+y is 0<(1 / 3)x+y<1, [Chemical formula 2] Li 3+z Ga [1-(1 / 3)z] F6 The z is in the range of −0.6≦z≦0.3.

[0033] That is, the cathode active material for an all-solid-state battery of the present invention may be in a form in which the lithium metal oxide cathode active material is coated with the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2. The coating may mean that the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 is physically and / or chemically bound to the surface of the core. In addition, the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 may cover the entire surface of the core or may be distributed in the form of islands or flakes on the surface of the core. When distributed in the form of islands or flakes, the compounds may be spaced apart from each other at a predetermined interval. Preferably, the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 may be distributed in a form in which the entire surface of the core is uniformly covered. When the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 is uniformly coated on the entire surface of the core, the coating layer of the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 prevents direct contact between the positive electrode active material and the solid electrolyte, thereby suppressing interfacial side reactions due to the difference in chemical potential of lithium ions. At the same time, the lithium concentration increases, ensuring a path for lithium ion migration, thereby reducing the interfacial resistance with the solid electrolyte.

[0034] The value of x cannot be less than 0. If x exceeds 0.3, it is not preferable because it may cause the formation of an LiF impurity phase and decrease the ionic conductivity.

[0035] If y is 0, Chemical Formula 1 does not contain gallium (Ga), so y must be greater than 0. If y is 1 or greater, aluminum (Al) in Chemical Formula 1 has a negative mole number, so y must be less than 1. Preferably, y is 0.1 <y<0.9であってもよい。

[0036] If (1 / 3)x + y is not less than 1, Chemical Formula 1 cannot contain aluminum, so (1 / 3)x + y must be less than 1. Also, since x is 0 ≦ x ≦ 0.3 and y is 0 < y < 1, it is natural that (1 / 3)x + y exceeds 0.

[0037] In Chemical Formula 1, x is 0 ≦ x ≦ 0.3, y is 0 < y < 1, and (1 / 3)x + y has 0 < (1 / 3)x + y < 1. Thus, the ionic conductivity of the compound represented by Chemical Formula 1 may be 9×10 -6 S / cm or more, preferably 1×10 -5 S / cm or more.

[0038] z is -0.6 to 0.3. If z is less than -0.6, by containing lithium at a low content, the effect of reducing the interfacial resistance between the positive electrode active material and the solid electrolyte is negligible, and the compound represented by Chemical Formula 2 can have a low ionic conductivity. Also, if z exceeds 0.3, the formation of the LiF impurity phase and the decrease in ionic conductivity occur, which is not preferable. Therefore, in Chemical Formula 2, z is -0.6 ≦ z ≦ 0.3, and preferably, -0.6 ≦ z < 0 may be acceptable.

[0039] In Chemical Formula 2, by having z of -0.6 ≦ z ≦ 0.3, the ionic conductivity of the compound represented by Chemical Formula 2 may be 8×10 -7 S / cm or more, preferably 1×10 -4 S / cm or more.

[0040] The thickness of the coating may be 10 to 200 nm, preferably 50 to 150 nm. A coating thickness of 10 to 200 nm can reduce the interfacial resistance between the positive electrode active material and the solid electrolyte. If the coating thickness is less than 10 nm, the interfacial resistance reduction effect is very small. However, if the coating thickness exceeds 200 nm, the increased interfacial resistance may prevent the positive electrode active material from achieving its inherent electrochemical performance, which is undesirable.

[0041] The compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 may be included in an amount of 0.1 to 5 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the core part. When the amount is within the range of 0.1 to 5 parts by weight, the effect of reducing the interfacial resistance can be obtained, but when the amount is outside this range, the interfacial resistance increases, which causes a problem that the electrochemical properties of the all-solid-state battery including this cannot be improved.

[0042] Method for manufacturing a positive electrode active material for an all-solid-state battery The present invention relates to a method for producing a positive electrode active material for an all-solid-state battery, the method comprising the steps of: (1) mixing a lithium precursor, an aluminum precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide, or mixing a lithium precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture; (2) heating and drying the mixture; and (3) calcining the heated and dried mixture;

[0043] The step (1) is a step of mixing a lithium precursor, an aluminum precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture, or a step of mixing a lithium precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture.

[0044] Specifically, a lithium precursor, an aluminum precursor, a gallium precursor, and a fluorine precursor may be dispersed in a suitable solvent to prepare a dispersion, and then a lithium metal oxide, which is a positive electrode active material, may be added to the dispersion to prepare a mixture.

[0045] Specifically, a lithium precursor, a gallium precursor, and a fluorine precursor may be dispersed in a suitable solvent to prepare a dispersion, and then a lithium metal oxide, which is a positive electrode active material, may be added to the dispersion to prepare a mixture.

[0046] The solvent is not particularly limited as long as it can be quickly removed without deteriorating the electrochemical properties of the lithium metal oxide, and anhydrous ethanol solvent can be used as a specific example.

[0047] The lithium precursor may be, for example, but not limited to, CH3COOLi·2H2O, LiOH, or LiNO3.

[0048] The aluminum precursor may be, for example, but not limited to, Al(NO3)3·9H2O or Al(OH)3.

[0049] The gallium precursor may be, for example, but not limited to, Ga(NO3)3·xH2O.

[0050] The fluorine precursor can be, for example, NHF or CH 15 The compound may be, but is not limited to, BF4N2.

[0051] The lithium precursor, aluminum precursor, gallium precursor, and fluorine precursor may be mixed in a molar ratio of 3:0.2:0.8:6 to 3.3:0.45:0.45:6.

[0052] The lithium precursor, the gallium precursor, and the fluorine precursor may be mixed in a molar ratio of 2.4:1.2:6 to 3.3:0.9:6.

[0053] The step (2) is a step of heating and drying the mixture prepared in the step (1).

[0054] The heating may be performed simultaneously with stirring so that the mixture has a uniformly dispersed phase without aggregation or precipitation in the solvent. The heating temperature may be 50 to 150°C, and is not particularly limited as long as it is a temperature at which the solvent can be evaporated. After the solvent is evaporated by heating, the mixture can be dried to obtain a powdery mixture. The drying may be performed by any method commonly used in the art without limitation. In the present invention, the powdery mixture was dried at a temperature of 50 to 100°C, but is not limited thereto.

[0055] The step (3) is a step of calcining the mixture heated and dried in the step (2).

[0056] The firing treatment may be carried out for 1 to 5 hours after raising the temperature to 250 to 500°C at a rate of 1 to 5°C / min. The firing treatment may be carried out while injecting argon gas (Ar).

[0057] Thereafter, the calcined mixture is cooled to room temperature to obtain the above-described cathode active material for an all-solid-state battery of the present invention. That is, the cathode active material for an all-solid-state battery may include a core portion containing a lithium metal oxide; and a coating portion located on the surface of the core portion and containing the compound of Chemical Formula 1 or the compound of Chemical Formula 2. The cathode active material for an all-solid-state battery may be prepared as described above.

[0058] Positive electrode for all-solid-state batteries The present invention relates to a positive electrode for an all-solid-state battery. The positive electrode may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder, and the positive electrode active material is the above-described positive electrode active material of the present invention.

[0059] The positive electrode may include a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, and the positive electrode active material, solid electrolyte, conductive material, and binder may be included in the positive electrode active material layer.

[0060] The positive electrode current collector is used to support the positive electrode active material layer and is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of a lithium secondary battery. For example, the positive electrode current collector may be made of any metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. The alloy may preferably be an aluminum-cadmium alloy. Alternatively, calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0061] The positive electrode current collector may have fine irregularities on its surface to strengthen the bonding force with the positive electrode active material, and may be in various forms such as a film, sheet, foil, mesh, net, porous material, foam, or nonwoven fabric.

[0062] The solid electrolyte may include one or more selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte, and preferably includes a sulfide-based solid electrolyte.

[0063] The sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and can include Li-PS-based glass and Li-PS-based glass ceramic.

[0064] Specifically, the sulfide-based solid electrolyte may include one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably includes one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite-type solid electrolytes. The sulfide-based solid electrolyte may be doped with a trace element, for example, Li6PS5Cl further doped with bromine (Br).

[0065] The polymer solid electrolyte is a composite of lithium salt and polymer resin, i.e., a polymer electrolyte material formed by adding polymer resin to solvated lithium salt, and has a capacity of about 1×10 -7 S / cm or more, preferably about 1×10 -5 It can exhibit ionic conductivity of S / cm or more.

[0066] Non-limiting examples of the polymer resin include polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc., and the polymer electrolyte may include one or more of these. Examples of the polymer resin include branched copolymers in which amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms), and / or phosphazene are copolymerized with a comonomer on a polyethylene oxide (PEO) main chain, comb-like polymers, and crosslinked polymers, and the polymer electrolyte may include one or more of these.

[0067] In the polymer solid electrolyte, the lithium salt is an ionizable lithium salt, and Li + X - The anion of such a lithium salt is not particularly limited, but can be represented by F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C- , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - Examples include:

[0068] The oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP compounds, LATP compounds, Li 1+x Ti 2-x Al x Si y (PO4) 3-y (where 0≦x≦1, 0≦y≦1), LiAl x Zr 2-x (PO4)3 (where 0≦x≦1, 0≦y≦1), LiTi x Zr 2-x The material may contain one or more compounds selected from (PO4)3 (where 0≦x≦1, 0≦y≦1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, Nasicon-based compounds, and LLZO-based compounds.

[0069] The conductive material electrically connects the current collector and the positive electrode active material and serves as a path for electrons to move from the current collector to the positive electrode active material. Any conductive material may be used without limitation as long as it does not cause a chemical change in a lithium secondary battery and has porosity and conductivity.

[0070] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, metallic fiber such as metal mesh, metallic powder such as copper, silver, nickel, aluminum, or organic conductive material such as polyphenylene derivative. The conductive materials may be used alone or in combination.

[0071] Currently, commercially available conductive materials include acetylene black series (products of Chevron Chemical Company or Gulf Oil Company, etc.), Ketjen Black EC series (products of Armak Company), Vulcan XC-72 (products of Cabot Company), and Super P (products of MMM). Examples include acetylene black, carbon black, and graphite.

[0072] The binder enhances the binding strength between the components constituting the positive electrode and between these components and the current collector, and any binder known in the industry can be used.

[0073] For example, the binder may be one or a mixture or copolymer of two or more selected from the group consisting of: fluororesin-based binders including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); rubber-based binders including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose-based binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol-based binders; polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester-based binders; and silane-based binders.

[0074] all solid state battery The present invention relates to an all-solid-state battery including a positive electrode; a negative electrode; and a solid electrolyte layer between the positive electrode and the negative electrode, wherein the positive electrode is the above-described positive electrode of the present invention.

[0075] The negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. Similarly to the positive electrode, the negative electrode may include a conductive material and a binder, if necessary. The negative electrode current collector, conductive material, and binder are as described above.

[0076] The negative electrode active material is a lithium ion (Li + Any material capable of reversibly intercalating or deintercalating lithium ions, or capable of reacting with lithium ions to reversibly form a lithium-containing compound, may be used.

[0077] For example, the negative electrode active material may be one or more carbon-based materials selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, ketjen black, Super P, graphene, fibrous carbon, Si-based materials, Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0<x≦1; 1≦y≦3; 1≦z≦8) and other metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxides; lithium titanium oxides, etc., may be included, but are not limited to only these.

[0078] Further, the negative electrode may include a negative electrode current collector and a coating layer including metal-carbon composite particles located on the negative electrode current collector. This may mean an anodeless negative electrode that does not contain a negative electrode active material.

[0079] During charging of the all-solid-state battery, lithium ions may pass through the coating layer and reach the surface of the negative electrode current collector, and these may be electrodeposited to form a lithium metal layer.

[0080] The metal-carbon composite particles may have a form in which carbon particles and metal particles are attached to each other or one is coated on the surface of the other, and may be physically or chemically bonded.

[0081] The carbon particles may include natural graphite, artificial graphite, hard carbon, soft carbon, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, carbon nanotubes, fullerene, carbon fiber, and fluorocarbon.

[0082] The metal particles are lithiophilic metals, such as Ni, Cu, Ag, Au, Pt, Al, Zn, and Bi, and may be one or a combination of two or more of these. The incorporation of the lithiophilic metal is advantageous for forming a stable and uniform lithium layer on the surface of the current collector.

[0083] The negative electrode may be manufactured by mixing a binder solution and the composite particles to prepare a slurry for forming a coating layer, and then coating the slurry on a negative electrode current collector and drying the coating layer. In this case, the binder may be a conventional binder used in the art.

[0084] The solid electrolyte layer is a layer of a solid electrolyte, and the solid electrolyte is as described above. Therefore, the solid electrolyte may include one or more selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte, and preferably includes a sulfide-based solid electrolyte.

[0085] As described above, the cathode active material of the present invention includes a coating portion including Chemical Formula 1 on the surface of a core portion including a lithium metal oxide, thereby preventing the lithium metal oxide, which is the cathode active material, from coming into direct contact with the solid electrolyte, thereby reducing side reactions that occur between the cathode active material and the solid electrolyte and thereby reducing interfacial resistance. Therefore, an all-solid-state battery including the same can achieve improved life characteristics. Therefore, the all-solid-state battery of the present invention can have excellent life characteristics.

[0086] The present invention will be described in more detail below with reference to examples. However, the following examples are for the purpose of illustrating the present invention, and the scope of the present invention is not limited to these examples.

[0087] <Production of a cathode active material in which the coating portion of the cathode active material includes a compound represented by Chemical Formula 1, and an all-solid-state battery including the same> Example 1-1. Production of positive electrode active material for all-solid-state batteries The precursor was dispersed in anhydrous ethanol by adding CH3COOLi·2H2O, Al(NO3)3·9H2O, Ga(NO3)3·xH2O, and NHF in a molar ratio of 3.3:0.45:0.45:6. 2.4925 g of NCM811 was added to the dispersion, which was then heated at 90°C for 2 hours while stirring at 200 rpm to evaporate the anhydrous ethanol solvent.

[0088] Thereafter, the mixture was dried at a temperature of 90°C for 2 hours, and then heated at a rate of 5°C / min while injecting argon gas, and then calcined at a temperature of 250°C for 2 hours. After that, the mixture was cooled to room temperature and pulverized to produce a positive electrode active material.

[0089] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+x Al [1-(1 / 3)x-y] Ga y It includes compounds of F6.

[0090] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 1-1 contained Li 3.3 Al 0.45 Ga 0.45 It was confirmed that the coating portion of the positive electrode active material of Example 1-1 contained LiF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, x was found to be 0.3 and y was found to be 0.45.

[0091] Example 1-2. Production of all-solid-state battery 100 mg of Li6PS5Cl was pressed at a pressure of 2.5 tons to produce a solid electrolyte layer with a thickness of about 10 mm.

[0092] The cathode active material prepared in Example 1-1, a conductive material (carbon fiber), and a solid electrolyte (Li6PS5Cl) were mixed in a weight ratio of 80:19:1, and the mixture was applied to a solid electrolyte pellet together with a cathode current collector and then pressed to prepare a cathode.

[0093] A Li-In alloy was used as the negative electrode.

[0094] The positive electrode, solid electrolyte layer, negative electrode, and SUS current collector were laminated in this order, and then pressed at a pressure of 3.5 tons to produce an all-solid-state battery of Example 1-2.

[0095] Example 2-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 1-1, except that the molar ratio of CH3COOLi·2H2O, Al(NO3)3·9H2O, Ga(NO3)3·xH2O, and NH4F was 3:0.2:0.8:6.

[0096] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+x Al [1-(1 / 3)x-y] Ga y It includes compounds of F6.

[0097] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 2-1 was Li3Al 0.2 Ga 0.8 It was confirmed that the coating portion of the positive electrode active material of Example 2-1 contained LiF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, x was found to be 0 and y was found to be 0.8.

[0098] Example 2-2. Production of all-solid-state battery An all-solid-state battery of Example 2-2 was produced in the same manner as in Example 1-2, except that the positive electrode active material of Example 2-1 was used.

[0099] Example 3-1. Production of positive electrode active material for all-solid-state battery A positive electrode active material was prepared in the same manner as in Example 1-1, except that the molar ratio of CH3COOLi·2H2O, Al(NO3)3·9H2O, Ga(NO3)3·xH2O, and NH4F was 3:0.5:0.5:6.

[0100] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+x Al [1-(1 / 3)x-y] Ga y It includes compounds of F6.

[0101] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 3-1 was Li3Al 0.5 Ga 0.5 It was confirmed that the coating portion of the positive electrode active material of Example 3-1 contained LiF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, x was found to be 0 and y was found to be 0.5.

[0102] Example 3-2. Production of all-solid-state battery An all-solid-state battery of Example 3-2 was produced in the same manner as in Example 1-2, except that the positive electrode active material of Example 3-1 was used.

[0103] Example 4-1. Production of positive electrode active material for all-solid-state battery A positive electrode active material was prepared in the same manner as in Example 1-1, except that the molar ratio of CH3COOLi·2H2O, Al(NO3)3·9H2O, Ga(NO3)3·xH2O, and NH4F was 3:0.8:0.2:6.

[0104] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+x Al [1-(1 / 3)x-y] Ga y It includes compounds of F6.

[0105] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 4-1 was Li3Al 0.8 Ga 0.2 It was confirmed that the coating portion of the positive electrode active material of Example 4-1 contained LiF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, x was found to be 0 and y was found to be 0.2.

[0106] Example 4-2. Production of all-solid-state battery An all-solid-state battery of Example 4-2 was produced in the same manner as in Example 1-2, except that the positive electrode active material of Example 4-1 was used.

[0107] Comparative Example 1-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 1-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 3:1:6.

[0108] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being made of NCM811, and the coating portion being made of Li 3+x Ga y It includes compounds of F6.

[0109] The coating portion was analyzed by ICP, and it was confirmed that the coating portion of the positive electrode active material of Comparative Example 1-1 contained Li3GaF6. That is, the coating portion of the positive electrode active material of Comparative Example 1-1 contained Li3GaF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga yIn F6, it was found that it does not contain aluminum, x is 0, y is 1, and (1 / 3)x+y is 1.

[0110] Comparative Example 1-2. Manufacturing of all-solid-state batteries An all-solid-state battery of Comparative Example 1-2 was produced in the same manner as in Example 1-2, except that the positive electrode active material of Comparative Example 1-1 was used.

[0111] Comparative Example 2-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 1-1, except that the molar ratio of CH3COOLi·2H2O, Al(NO3)3·9H2O, and NH4F was 3.3:0.9:6.

[0112] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being made of NCM811, and the coating portion being made of Li 3+x Al [1-(1 / 3)x-y] It includes compounds of F6.

[0113] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Comparative Example 2-1 contained Li 3.3 Al 0.9 It was confirmed that the coating portion of the positive electrode active material of Comparative Example 2-1 contained LiF6, which is represented by Chemical Formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, it was found that it contained no gallium, x was 0.3, and y was 0.

[0114] Comparative Example 2-2. Manufacturing of all-solid-state batteries An all-solid-state battery of Comparative Example 2-2 was produced in the same manner as in Example 1-2, except that the positive electrode active material of Comparative Example 2-1 was used.

[0115] <Production of a cathode active material in which the coating portion of the cathode active material includes a compound represented by Chemical Formula 2, and an all-solid-state battery including the same> Example 5-1. Production of positive electrode active material for all-solid-state battery The precursor was dispersed in anhydrous ethanol by adding CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NHF in a molar ratio of 2.4:1.2:6 to the dispersion. 2.4925 g of NCM811 was added to the dispersion, which was then heated at 90°C for 2 hours while stirring at 200 rpm to evaporate the anhydrous ethanol solvent.

[0116] Thereafter, the mixture was dried at a temperature of 90°C for 2 hours, and then heated at a rate of 5°C / min while injecting argon gas, and then calcined at a temperature of 250°C for 2 hours. After that, the mixture was cooled to room temperature and pulverized to produce a positive electrode active material.

[0117] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z] It includes compounds of F6.

[0118] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 5-1 contained Li 2.4 Ga 1.2 It was confirmed that the coating portion of the positive electrode active material of Example 5-1 contained LiF6, which is represented by the chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be -0.6.

[0119] Example 5-2. Production of all-solid-state battery 100 mg of Li6PS5Cl was pressed at a pressure of 2.5 tons to produce a solid electrolyte layer with a thickness of about 10 mm.

[0120] The positive electrode active material prepared in Example 5-1, a conductive material (carbon fiber), and a solid electrolyte (Li6PS5Cl) were mixed in a weight ratio of 80:19:1, and the mixture was applied to a solid electrolyte pellet together with a positive electrode current collector and then pressed to prepare a positive electrode.

[0121] A Li-In alloy was used as the negative electrode.

[0122] The positive electrode, solid electrolyte layer, negative electrode, and SUS current collector were laminated in this order, and then pressed at a pressure of 3.5 tons to produce an all-solid-state battery of Example 5-2.

[0123] Example 6-1. Production of positive electrode active material for all-solid-state battery A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 2.7:1.1:6.

[0124] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z] It includes compounds of F6.

[0125] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 6-1 contained Li 2.7 Ga 1.1 It was confirmed that the coating portion of the positive electrode active material of Example 6-1 contained LiF6, which is represented by the chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be -0.3.

[0126] Example 6-2. Production of all-solid-state battery An all-solid-state battery of Example 6-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Example 6-1 was used.

[0127] Example 7-1. Production of positive electrode active material for all-solid-state battery A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 3:1:6.

[0128] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z]It includes compounds of F6.

[0129] The coating portion was analyzed by ICP, and it was confirmed that the coating portion of the positive electrode active material of Example 7-1 contained Li3GaF6. That is, the coating portion of the positive electrode active material of Example 7-1 contained Li3GaF6, which is represented by the chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be 0.

[0130] Example 7-2. Production of all-solid-state battery An all-solid-state battery of Example 7-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Example 7-1 was used.

[0131] Example 8-1. Production of positive electrode active material for all-solid-state battery A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 3.3:0.9:6.

[0132] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z] It includes compounds of F6.

[0133] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Example 8-1 contained Li 3.3 Ga 0.9 It was confirmed that the coating portion of the positive electrode active material of Example 8-1 contained LiF6, which is represented by the chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be 0.3.

[0134] Example 8-2. Production of all-solid-state battery An all-solid-state battery of Example 8-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Example 8-1 was used.

[0135] Comparative Example 3-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Al(NO3)3·9H2O, and NH4F was 3:1:6.

[0136] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being made of NCM811, and the coating portion being made of Li 3+z Al [1-(1 / 3)z] It includes compounds of F6.

[0137] The coating portion was analyzed by ICP, and it was confirmed that the coating portion of the cathode active material of Comparative Example 3-1 contained Li3AlF6. That is, the coating portion of the cathode active material of Comparative Example 3-1 contained Li3AlF6, which is represented by the chemical formula 2. 3+z Ga [1-(1 / 3)z] It is F6, but contains aluminum instead of gallium.

[0138] Comparative Example 3-2. Manufacture of all-solid-state batteries An all-solid-state battery of Comparative Example 3-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Comparative Example 3-1 was used.

[0139] Comparative Example 4-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 3.45:0.85:6.

[0140] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z] It includes compounds of F6.

[0141] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Comparative Example 4-1 contained Li 3.45 Ga0.85 It was confirmed that the coating portion of the positive electrode active material of Comparative Example 4-1 contained LiF6, which is represented by Chemical Formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be 0.45.

[0142] Comparative Example 4-2. Manufacture of all-solid-state batteries An all-solid-state battery of Comparative Example 4-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Comparative Example 4-1 was used.

[0143] Comparative Example 5-1. Production of positive electrode active material for all-solid-state batteries A positive electrode active material was prepared in the same manner as in Example 5-1, except that the molar ratio of CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F was 3.6:0.8:6.

[0144] The positive electrode active material includes a core portion and a coating portion located on the surface of the core portion, the core portion being NCM811, and the coating portion being Li 3+z Ga [1-(1 / 3)z] It includes compounds of F6.

[0145] As a result of ICP analysis of the coating portion, it was found that the coating portion of the positive electrode active material of Comparative Example 5-1 contained Li 3.6 Ga 0.8 It was confirmed that the coating portion of the positive electrode active material of Comparative Example 5-1 contained LiF6, which is represented by Chemical Formula 2. 3+z Ga [1-(1 / 3)z] In F6, z was found to be 0.6.

[0146] Comparative Example 5-2. Manufacture of all-solid-state battery An all-solid-state battery of Comparative Example 5-2 was produced in the same manner as in Example 5-2, except that the positive electrode active material of Comparative Example 5-1 was used.

[0147] Experimental Example 1. Measurement of ionic conductivity of the coating area of ​​the positive electrode active material The ionic conductivity of the coating portions of the positive electrode active materials produced in Examples 1-1 to 8-1 and Comparative Examples 1-1 to 5-1 was measured.

[0148] The ionic conductivity was measured by electrochemical impedance spectroscopy (EIS) in a frequency range of 5.0 MHz to 7.0 MHz with an alternating current (AC) voltage of 10 mV applied to a symmetric cell composed of a solid electrolyte (Li6PS5Cl) / ionic conductor / solid electrolyte (Li6PS5Cl).

[0149] The results of Examples 1-1 to 4-1 and Comparative Examples 1-1 and 2-1 are shown in Table 1 below, and the results of Examples 5-1 to 8-1 and Comparative Examples 3-1 to 5-1 are shown in Table 2 below.

[0150]

Table 1

[0151] In Examples 1-1 to 4-1, the coating portion satisfies the ranges of x, y, and (1 / 3)x + y in Chemical Formula 1. On the other hand, in Comparative Examples 1-1 to 2-1, the coating portions contain Li3GaF6 and Li 3.3 Al 0.9 F6, respectively, and do not contain aluminum and gallium, respectively. That is, in Comparative Example 1-1, y is 1, and in Comparative Example 2-1, y is 0.

[0152] From the results in Table 1 above, it was found that in Chemical Formula 1, when 0 ≦ x ≦ 0.3, 0 < y < 1, and 0 < (1 / 3)x + y < 1 are satisfied, the ionic conductivity of the coating portion, which is a compound represented by Chemical Formula 1, is very high. On the other hand, when y is outside the above range, the ionic conductivity of the coating portion of the positive electrode active material in Comparative Example 2-1, which does not contain gallium, shows a very low result, indicating that the effect of improving ionic conductivity cannot be obtained.

[0153]

Table 2

[0154] In Examples 5-1 to 8-1, the coating portion was Li 2.4 Ga 1.2 F6, Li 2.7 Ga 1.1 F6, Li3GaF6 and Li 3.3 Al 0.9 F6 and satisfy the range of z in the chemical formula 2. On the other hand, in Comparative Examples 3-1 to 5-1, the coating portion contains Li3AlF6, Li 3.45 Ga 0.85 F6 and Li 3.6 Ga 0.8 Those containing F6, those containing aluminum instead of gallium in Chemical Formula 2, and those in which x exceeds 0.3, which is outside the range of x in Chemical Formula 2.

[0155] From the above results, it was found that when -0.6≦z≦0.3 is satisfied in Chemical Formula 2, the ionic conductivity of the coating portion, which is the compound represented by Chemical Formula 2, is very high. On the other hand, when z is outside this range, the ionic conductivity of the coating portion is very low, and it was found that the effect of improving ionic conductivity cannot be obtained.

[0156] Experimental Example 2: Measurement of the potential stability window of the coating area of ​​the positive electrode active material The electrochemical stability of the coating portion of the positive electrode active materials prepared in Examples 2-1 to 3-1 and Comparative Examples 1-1 to 2-1 was measured.

[0157] The electrochemical stability was measured using a biologic electrochemical device by linear sweep voltammetry (LSV) measurement method at a rate of 1.0 mV / s from 0 V to 5 V, and the results are shown in Table 3 below.

[0158] [Table 3]

[0159] In Examples 2-1 and 3-1, the coating part satisfies the ranges of x, y, and (1 / 3)x + y in Chemical Formula 1. On the other hand, in Comparative Examples 1-1 and 2-1, the coating parts contain Li3GaF6 and Li 3.3 Al 0.9 F6 respectively, and do not contain aluminum and gallium respectively. That is, in Comparative Example 1-1, y = 1, and in Comparative Example 2-1, y = 0.

[0160] From the results in Table 3 above, it was found that when 0 ≦ x ≦ 0.3, 0 < y < 1, and 0 < (1 / 3)x + y < 1 are satisfied in Chemical Formula 1, the electrochemical stability of the coating part, which is a compound represented by Chemical Formula 1, is very high. On the other hand, when y is outside the above range, the coating part of the positive electrode active material in Comparative Example 1-1 that does not contain aluminum shows a very low electrochemical stability, indicating that the effect of improving the electrochemical stability cannot be obtained.

[0161] From the results of Experimental Examples 1 and 2 above, it was confirmed that the positive electrode active material of the present invention has excellent ion conductivity and electrochemical stability.

[0162] Experimental Example 3: Evaluation of charge / discharge and life characteristics of all-solid-state batteries The charge-discharge and life characteristics of all-solid-state batteries of Example 2-2, Example 3-2, Example 5-2, Example 6-2, and Comparative Examples 1-2, 2-2, 4-2, and 5-2 were measured.

[0163] The charge-discharge characteristics were measured by charging the all-solid-state battery at a temperature of 25°C in the CCCV mode at 0.1C until it reached 3.7V, and then discharging it at a constant current until it reached 1.9V. The results are shown in Tables 4 and 5 below.

[0164] The life characteristic measurement was carried out by charging the all-solid-state battery at a temperature of 25°C in the CCCV mode at 0.5C until it reached 3.7V after the measurement of the charge-discharge characteristics, and then discharging it at a constant current until it reached 1.9V and performing 100 charge-discharges. The measurement was made by the capacity retention rate at that time, and the results are shown in Tables 6 and 7 below.

[0165] [Table 4]

[0166] [Table 5]

[0167] [Table 6]

[0168] [Table 7]

[0169] From the results of Tables 4 and 6, the positive electrode active materials contained in the all-solid-state batteries of Examples 2-2 and 3-2 are superior in ionic conductivity and electrochemical stability to the positive electrode active materials contained in the all-solid-state batteries of Comparative Examples 1-2 and 2-2. Therefore, the all-solid-state batteries of Examples 2-2 and 3-2 showed improved initial charge / discharge capacity and life characteristics compared to the all-solid-state batteries of Comparative Examples 1-2 and 2-2.

[0170] Furthermore, from the results of Tables 5 and 7, the positive electrode active materials contained in the all-solid-state batteries of Examples 5-2 and 6-2 have superior ionic conductivity to the positive electrode active materials contained in the all-solid-state batteries of Comparative Examples 4-2 and 5-2, and therefore the all-solid-state batteries of Examples 5-2 and 6-2 showed improved initial charge / discharge capacities and life characteristics compared to the all-solid-state batteries of Comparative Examples 4-2 and 5-2.

Claims

1. a core comprising a lithium metal oxide; and a coating portion located on a surface of the core portion and containing a compound represented by the following Chemical Formula 1 or a compound represented by the following Chemical Formula 2: [Chemical formula 1] Li ３＋ｘ Al ［１－（１／３）ｘ－ｙ］ Ga ｙ F ６ The x is 0≦x≦0.3, The y is 0<y<1, (1 / 3)x+y satisfies 0<(1 / 3)x+y<1, [Chemical formula 2] Li ３＋ｚ Ga ［１－（１／３）ｚ］ F ６ The z is in the range of −0.6≦z≦0.

3.

2. 2. The positive electrode active material for an all-solid-state battery according to claim 1, wherein y satisfies the formula 0.1<y<0.

9.

3. 2. The positive electrode active material for an all-solid-state battery according to claim 1, wherein z satisfies −0.6<z<0.

4. The cathode active material for an all-solid-state battery according to claim 1 , wherein the coating portion has a thickness of 10 nm or more and 200 nm or less.

5. 2. The positive electrode active material for an all-solid-state battery according to claim 1, wherein the compound represented by Chemical Formula 1 or the compound represented by Chemical Formula 2 is contained in an amount of 0.1 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of the core part:

6. The ionic conductivity of the compound represented by Chemical Formula 1 is 9×10 －６ S / cm or more, The ionic conductivity of the compound represented by Chemical Formula 2 is 8×10 －７ The positive electrode active material for an all-solid-state battery according to claim 1, wherein the conductivity is 1.5 S / cm or more.

7. (1) mixing a lithium precursor, an aluminum precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture, or mixing a lithium precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to prepare a mixture; (2) heating and drying the mixture; and (3) a step of calcining the heated and dried mixture.

8. 8. The method for producing a positive electrode active material for an all-solid-state battery according to claim 7, wherein the lithium precursor, the aluminum precursor, the gallium precursor, and the fluorine precursor are mixed in a molar ratio of 3.3:0.45:0.45:6 to 3:0.8:0.2:

6.

9. 8. The method for producing a positive electrode active material for an all-solid-state battery according to claim 7, wherein the lithium precursor, the gallium precursor, and the fluorine precursor are mixed in a molar ratio of 2.4:1.2:6 to 3.3:0.9:

6.

10. 8. The method for producing a positive electrode active material for an all-solid-state battery according to claim 7, wherein the firing treatment is performed by raising the temperature to 250°C or higher and 500°C or lower at a rate of 1°C / min or higher and 5°C / min or lower, and then for 1 hour or higher and 5 hours or lower.

11. A positive electrode for an all-solid-state battery, comprising the positive electrode active material according to any one of claims 1 to 6, a solid electrolyte, a conductive material, and a binder.

12. An all-solid-state battery comprising: the positive electrode according to claim 11; a negative electrode; and a solid electrolyte layer between the positive electrode and the negative electrode.

13. 13. The all-solid-state battery according to claim 12, wherein the solid electrolyte comprises at least one selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte.

14. The all-solid-state battery according to claim 13 , wherein the solid electrolyte comprises a sulfide-based solid electrolyte.

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