Positive electrode active material for all-solid-state batteries, method for manufacturing the same, positive electrode for all-solid-state batteries containing 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 priority rights under Korean Patent Application No. 10-2023-0154597 dated November 9, 2023, Korean Patent Application No. 10-2023-0154618 dated November 9, 2023, and Korean Patent Application No. 10-2024-0144764 dated October 22, 2024, and incorporates all the contents disclosed in the documents of said Korean Patent Applications as part of this Specification.

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

[0003] Lithium-ion batteries are widely used as power sources for portable devices, including IT mobile devices, and in recent years, the market has been growing rapidly, from small lithium-ion batteries to medium and large-sized batteries. In particular, their use as automotive batteries is on the rise. To use lithium-ion batteries as power sources for electric vehicles, high energy density and high output characteristics are required, and ensuring safety is especially important.

[0004] Conventional lithium-ion batteries use liquid, non-aqueous organic electrolytes, which pose a risk of ignition and explosion. Since explosion accidents involving products using this technology continue to occur, resolving these issues is a matter of urgency.

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

[0006] Candidate solid electrolytes used in 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 capacity of 1 × 10⁻⁶.-2 It exhibits high lithium-ion conductivity values ​​of S / cm or higher and has a wide potential window of 5V or more, resulting in less degradation of characteristics even in extreme environments, and offering significant advantages in the design of high-energy-density lithium-ion secondary batteries.

[0007] In all-solid-state batteries using sulfide-based solid electrolytes, there is a problem in that the capacity is not properly realized due to high interfacial resistance generated at the interface between the positive electrode active material and the sulfide-based solid electrolyte. The main causes of such 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 chemical potential difference between lithium ions in the positive electrode active material and the solid electrolyte, and 2) the formation of an interfacial impurity layer due to chemical reactions at the interface between the positive electrode active material and the solid electrolyte.

[0008] To solve the aforementioned problems, a technique has been applied to introduce a coating layer on the surface of the positive electrode active material, and lithium oxide of Li-MO (where M is B, Al, Zr, P, Ti, Nb, or W) is known as the material for the coating layer. However, the coating layer materials known to date are still insufficient to solve the aforementioned problems, and therefore, 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 is currently needed. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent No. 2017-0070239 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] To solve the aforementioned problems, the inventors conducted multifaceted research and discovered that coating the surface of the lithium metal oxide, which is the positive electrode active material, with lithium aluminum gallium fluoride, which is the compound shown in chemical formula 1 below, or lithium gallium fluoride, which is the compound shown in chemical formula 2 below, can reduce the interfacial resistance between the positive electrode active material and the solid electrolyte, thus completing the present invention.

[0011] Accordingly, the present invention aims to provide a positive electrode active material for all-solid-state batteries that can reduce the interfacial resistance between the positive electrode active material and the solid electrolyte, a method for producing the same, and a positive electrode containing the same.

[0012] Furthermore, the present invention aims to provide an all-solid-state battery including the positive electrode that has excellent lifespan characteristics and discharge capacity. [Means for solving the problem]

[0013] In order to achieve the aforementioned objective, The present invention includes a core portion containing a lithium metal oxide; and The present invention provides a positive electrode active material for an all-solid-state battery, comprising a coating portion located on the 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;

[0014] [Chemical formula 1] Li 3+x Al [1-(1 / 3)x-y] Ga y F6 The aforementioned x is 0 ≤ x ≤ 0.3, The aforementioned y is 0 <y<1であり、 (1 / 3)x+y satisfies 0 < (1 / 3)x+y < 1. [Chemical formula 2] Li 3+z Ga [1-(1 / 3)z] F6 The above z is -0.6 ≤ z ≤ 0.3.

[0015] Furthermore, the present invention also includes the step 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 produce a mixture; (2) The step of heating and drying the mixture; and (3) The present invention provides a method for producing a positive electrode active material for an all-solid-state battery, comprising the step of calcining the heated and dried mixture.

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

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

[0018] The positive electrode active material for all-solid-state batteries of the present invention includes a coating portion on the surface of the core portion containing the lithium metal oxide positive electrode active material, which contains a compound represented by the following chemical formula 1 or the compound represented by the chemical formula 2. This makes it possible to suppress side reactions occurring between the positive electrode active material and the solid electrolyte and to reduce interfacial resistance.

[0019] As a result, the all-solid-state battery containing the positive electrode active material can have improved lifespan characteristics and discharge capacity. [Modes for carrying out the invention]

[0020] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their inventions.

[0021] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates a different meaning. In the present invention, terms such as "comprising" or "having" specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and it should not be understood as precluding the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0022] Hereinafter, the present invention will be described in more detail.

[0023] All-solid-state batteries use a solid electrolyte to conduct lithium ions, whereby the movement of lithium ions due to charge and discharge is performed in a solid state. That is, since lithium ions can only move through the actual contact site between the positive electrode and the solid electrolyte in all-solid-state batteries, minimizing the interfacial resistance between the positive electrode and the solid electrolyte can improve the performance of all-solid-state batteries.

[0024] However, side reactions occur at the actual contact site between the positive electrode and the solid electrolyte, thereby increasing the interfacial resistance.

[0025] Therefore, in the present invention, an attempt was made to provide a positive electrode active material capable of reducing the interfacial resistance between the positive electrode and the solid electrolyte.

[0026] Cathode active material for all-solid-state batteries The present invention relates to a positive electrode active material for an all-solid-state battery including a core part containing a lithium metal oxide; and a coating part located on the surface of the core part and containing 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 where \(x\) satisfies \(0\leq x\leq0.3\), where \(y\) satisfies \(0 < y < 1\), where \((1 / 3)x + y\) satisfies \(0 < (1 / 3)x + y < 1\), [Chemical Formula 2] Li 3+z Ga [1-(1 / 3)z] F6 where \(z\) satisfies \(-0.6\leq z\leq0.3\).

[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), lithium nickel oxide (LiNiO2), or 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 \(0 < x\leq1.5\), \(y\) satisfies \(0 < y\leq1\)); Chemical formula Li 1+x Mn 2-x O4 (\(0\leq x\leq0.33\)), 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 type lithium nickel oxide represented as 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 oxide represented as 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 This may include, but is not limited to, lithium manganese composite oxides with a spinel structure represented by O4; LiCoPO4; or LiFePO4; etc.

[0031] The coating portion is located on the surface of the core portion and may contain 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 The aforementioned x is 0 ≤ x ≤ 0.3, The aforementioned y is 0 <y<1であり、 (1 / 3)x+y satisfies 0 < (1 / 3)x+y < 1. [Chemical formula 2] Li 3+z Ga [1-(1 / 3)z] F6 The above z is -0.6 ≤ z ≤ 0.3.

[0033] In other words, the positive electrode active material for the all-solid-state battery of the present invention may be in a form in which the lithium metal oxide, which is the positive electrode 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 bonded to the surface of the core. The compound represented by chemical formula 1 or the compound represented by chemical formula 2 may cover the entire surface of the core, or it may be distributed on the surface of the core in island type or flake form, and if it is distributed in island type or flake form, it may be separated from each other by 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 that uniformly covers the entire surface of the core. When the compound represented by chemical formula 1 or the compound represented by chemical formula 2 is uniformly coated over 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 chemical potential difference of lithium ions. At the same time, the lithium concentration increases, and a path for lithium ion movement is secured, thereby reducing the interfacial resistance with the solid electrolyte.

[0034] The aforementioned x cannot have a value less than 0. Furthermore, if x exceeds 0.3, it is undesirable because it leads to the formation of the LiF impurity phase and a decrease in ionic conductivity.

[0035] If y is 0, then chemical formula 1 will not contain gallium (Ga), so y must be greater than 0. Also, if y is 1 or greater, then aluminum (Al) in chemical formula 1 will have a negative number of moles, 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. Therefore, (1 / 3)x + y must be less than 1. Also, since x satisfies 0 ≦ x ≦ 0.3 and y satisfies 0 < y < 1, it is natural that (1 / 3)x + y exceeds 0.

[0037] In Chemical Formula 1, x satisfies 0 ≦ x ≦ 0.3, y satisfies 0 < y < 1, and (1 / 3)x + y satisfies 0 < (1 / 3)x + y < 1. Due to this, the ionic conductivity of the compound represented by Chemical Formula 1 can be 9×10 -6 S / cm or more, and preferably, it can also be 1×10 -5 S / cm or more.

[0038] For z, it 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 satisfies -0.6 ≦ z ≦ 0.3, and preferably, it may also satisfy -0.6 ≦ z < 0.

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

[0040] Furthermore, the thickness of the coating portion may be 10 to 200 nm, and preferably 50 to 150 nm. By having a coating portion thickness of 10 to 200 nm, a reduction in interfacial resistance between the positive electrode active material and the solid electrolyte can be obtained. If the thickness of the coating portion is less than 10 nm, the reduction in interfacial resistance will be very small, and if the thickness of the coating portion exceeds 200 nm, the increase in interfacial resistance may prevent the positive electrode active material from exhibiting its original electrochemical performance, which is undesirable.

[0041] The compound represented by chemical formula 1 or the compound represented by chemical formula 2 is 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. Within the range of 0.1 to 5 parts by weight, a reduction in interfacial resistance can be obtained, but outside this range, the interfacial resistance increases, which presents a problem in that the electrochemical properties of the all-solid-state battery containing it cannot be improved.

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

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

[0044] Specifically, this may involve preparing a dispersion by dispersing a lithium precursor, an aluminum precursor, a gallium precursor, and a fluorine precursor in a suitable solvent, and then adding a lithium metal oxide, which is a positive electrode active material, to the dispersion to produce a mixture.

[0045] Specifically, this may involve preparing a dispersion by dispersing a lithium precursor, a gallium precursor, and a fluorine precursor in a suitable solvent, and then adding a lithium metal oxide, which is a positive electrode active material, to the dispersion to produce a mixture.

[0046] The solvent is not particularly limited as long as it can rapidly remove the lithium metal oxide without degrading its electrochemical properties, and anhydrous ethanol can be used as one specific example.

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

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

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

[0050] The fluorine precursor is, for example, NH4F or C8H 15 BF4N2 is also an option, but it is not limited to these.

[0051] Furthermore, 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] Furthermore, the lithium precursor, gallium precursor, and fluorine precursor may be mixed in a molar ratio of 2.4:1.2:6 to 3.3:0.9:6.

[0053] The (2) step is to heat and dry the mixture produced in the (1) step.

[0054] The heating may be performed simultaneously with stirring so that the mixture does not aggregate and precipitate in the solvent and has a uniformly dispersed phase. 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 heating and evaporating the solvent, the mixture can be dried to obtain a powder. The drying can be carried out without limitation using methods used in the industry, and in this invention, the powder mixture was dried at a temperature of 50 to 100°C, but is not limited thereto.

[0055] The third step is to calcine the mixture that has been heated and dried in the second step.

[0056] The aforementioned firing process may be carried out by raising the temperature to 250-500°C at a rate of 1-5°C / min, followed by 1-5 hours. Furthermore, the firing process may be carried out while injecting argon gas (Ar).

[0057] Subsequently, the calcined mixture can be cooled to room temperature to obtain the positive electrode active material for the all-solid-state battery of the present invention. That is, the positive electrode active material for the 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 positive electrode active material for the all-solid-state battery is 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, wherein 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 positive electrode active material of the present invention as described above.

[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. Therefore, 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 for supporting 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 the lithium secondary battery. For example, the positive electrode current collector may be any one 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. As the alloy, an aluminum-cadmium alloy may be preferably used. Other options include calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer.

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

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

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

[0064] Specifically, the sulfide-based solid electrolyte may contain 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 contains one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The Li6PS5Cl, Li6PS5Br, and Li6PS5I mentioned above may be argyrodite-type solid electrolytes. Furthermore, the sulfide-based solid electrolyte may be in a form doped with trace amounts of elements; for example, Li6PS5Cl may be further doped with bromine (Br).

[0065] The aforementioned polymer solid electrolyte is a composite of a lithium salt and a polymer resin, that is, a polymer electrolyte material formed by adding a polymer resin to a solvated lithium salt, and is approximately 1 × 10⁻⁶ -7 S / cm or more, preferably about 1 × 10 -5 It can exhibit ionic conductivity of S / cm or higher.

[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, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, and may contain one or more of these. Furthermore, as the polymer electrolyte, examples of polymer resins include branched copolymers obtained by copolymerizing a PEO (polyethylene oxide) main chain with amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms) and / or phosphazene as copolymerizers, comb-like polymers, and crosslinked polymers, and may contain one or more of these.

[0067] In the polymer solid electrolyte, the lithium salt is an ionizable lithium salt, Li + X - It can be expressed as follows. There are no particular restrictions on the anion of such lithium salt, but 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 the following.

[0068] The oxide-based solid electrolyte may contain oxygen (O) and have ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, LLTO compounds, 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 (Here, 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 (PO4)3 (where 0≦x≦1, 0≦y≦1), may contain one or more compounds selected from LISICON compounds, LIPON compounds, perovskite compounds, NASICON compounds, and LLZO compounds.

[0069] The conductive material electrically connects the current collector and the positive electrode active material, acting as a pathway for electrons to move from the current collector to the positive electrode active material. It can be used without limitation as long as it does not undergo chemical changes in a lithium secondary battery and is porous and conductive.

[0070] For example, the conductive material can be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, metallic fibers such as metal mesh; metallic powders such as copper, silver, nickel, and aluminum; or organic conductive materials such as polyphenylene derivatives. The conductive materials can be used individually or in combination.

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

[0072] Furthermore, the binder enhances the bonding force between the components constituting the positive electrode and between them and the current collector, and any binder known in the industry can be used.

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

[0074] all solid state battery The present invention relates to an all-solid-state battery comprising 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 positive electrode of the present invention as described above.

[0075] The negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector. Furthermore, the negative electrode, like the positive electrode, may optionally include a conductive material and a binder. In this case, the negative electrode current collector, conductive material, and binder are as described above.

[0076] The aforementioned negative electrode active material is lithium ion (Li + Any substance that can reversibly intercalate or deintercalate lithium, or react with lithium ions to reversibly form lithium-containing compounds, is acceptable.

[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, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) and other metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; 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 thereto.

[0078] Also, the negative electrode may include a negative electrode current collector and a coating layer containing 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 adhered to each other or one is coated on the surface of the other, and may be physically or chemically bonded.

[0081] The aforementioned 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, fullerenes, carbon fibers, and fluorinated carbon.

[0082] The aforementioned metal particles are lithiophilic metals, such as Ni, Cu, Ag, Au, Pt, Al, Zn, and Bi, and may be one or more of these in combination. Introducing these lithium-philic metals 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 produce a slurry for forming a coating layer, and then applying and drying the slurry onto a negative electrode current collector. In this case, the binder may be a conventional binder used in the industry.

[0084] The solid electrolyte layer consists of a solid electrolyte in a layered structure, and the solid electrolyte is as described above. Therefore, the solid electrolyte may contain one or more selected from the group consisting of sulfide-based solid electrolytes, polymer-based solid electrolytes, and oxide-based solid electrolytes, and preferably contains a sulfide-based solid electrolyte.

[0085] As described above, the positive electrode active material of the present invention includes a coating portion containing chemical formula 1 on the surface of the core portion containing lithium metal oxide. This prevents the lithium metal oxide, which is the positive electrode active material, from coming into direct contact with the solid electrolyte, thereby reducing side reactions between the positive electrode active material and the solid electrolyte, and consequently reducing interfacial resistance. Therefore, an all-solid-state battery containing this can achieve improved lifespan characteristics. Thus, the all-solid-state battery of the present invention can have excellent lifespan characteristics.

[0086] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

[0087] <Manufacturing of a positive electrode active material in which the coating portion of the positive electrode active material contains a compound represented by chemical formula 1, and an all-solid-state battery containing the same> Example 1-1. Production of positive electrode active material for all-solid-state batteries CH3COOLi·2H2O, Al(NO3)3·9H2O, Ga(NO3)3·xH2O and NH4F were added to an anhydrous ethanol solvent in a molar ratio of 3.3:0.45:0.45:6 to disperse the precursors. After adding 2.4925 g of NCM811 to the dispersion, it was heated at 90 °C for 2 hours while stirring at 200 rpm to evaporate the anhydrous ethanol solvent.

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

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

[0090] As a result of ICP analysis of the coating part, it was confirmed that the coating part of the positive electrode active material of Example 1-1 contains Li 3.3 Al 0.45 Ga 0.45 F6. That is, in Li 3+x Al [1-(1 / 3)x-y] Ga y F6 of Chemical Formula 1, it was found that x is 0.3 and y is 0.45.

[0091] Examples 1-2. Manufacturing of all-solid-state batteries 100 mg of Li6PS5Cl was pressurized at a pressure of 2.5 ton to produce a solid electrolyte layer with a thickness of about 10 mm.

[0092] The positive electrode active material, conductive material (carbon fiber), and solid electrolyte (Li6PS5Cl) produced in Example 1-1 were mixed at 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 produce a positive electrode.

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

[0094] After laminating the positive electrode, solid electrolyte layer, negative electrode, and SUS current collector in this order, they were pressed under a pressure of 3.5 tons to produce the all-solid-state battery of Example 1-2.

[0095] Example 2-1. Production of positive electrode active material for all-solid-state batteries 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, the same procedure as in Example 1-1 was carried out to produce a positive electrode active material.

[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 is NCM811, and the coating portion is Li 3+x Al [1-(1 / 3)x-y] Ga y a compound of F6.

[0097] As a result of ICP analysis of the coating portion, it was confirmed that the coating portion of the positive electrode active material of Example 2-1 contains Li3Al 0.2 Ga 0.8 F6. That is, in the coating portion of the positive electrode active material of Example 2-1, Li 3+x Al [1-(1 / 3)x-y] Ga y in F6, it was found that x is 0 and y is 0.8.

[0098] Example 2-2. Manufacturing of an all-solid-state battery An all-solid-state battery of Example 2-2 was manufactured by following the same procedure 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 batteries The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga y It contains the F6 compound.

[0101] ICP analysis of the aforementioned coating portion revealed that the coating portion of the positive electrode active material in Example 3-1 is Li3Al 0.5 Ga 0.5 It was confirmed that it contains F6. That is, the coating portion of the positive electrode active material in Example 3-1 contains Li, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, it was found that x is 0 and y is 0.5.

[0102] Example 3-2. Manufacturing of an all-solid-state battery The all-solid-state battery of Example 3-2 was manufactured 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 batteries The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga y It contains the F6 compound.

[0105] ICP analysis of the aforementioned coating portion revealed that the coating portion of the positive electrode active material in Example 4-1 is Li3Al 0.8 Ga 0.2 It was confirmed that it contains F6. That is, the coating portion of the positive electrode active material in Example 4-1 contains Li, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, it was found that x is 0 and y is 0.2.

[0106] Example 4-2. Manufacturing of an all-solid-state battery An all-solid-state battery of Example 4-2 was manufactured 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 The positive electrode active material was produced 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 NCM811 and the coating portion being Li 3+x Ga y It contains the F6 compound.

[0109] ICP analysis of the coating portion confirmed that the coating portion of the positive electrode active material of Comparative Example 1-1 contained Li3GaF6. In other words, the coating portion of the positive electrode active material of Comparative Example 1-1 contained Li3GaF6, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga yIn F6, it was found that aluminum was not included, x was 0, y was 1, and (1 / 3)x+y was 1.

[0110] Comparative Example 1-2. Manufacturing of All-Solid-State Batteries A solid-state battery of Comparative Example 1-2 was manufactured 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 The positive electrode active material was produced 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 NCM811 and the coating portion being Li 3+x Al [1-(1 / 3)x-y] It contains the F6 compound.

[0113] As a result of ICP analysis of the aforementioned coating portion, the coating portion of the positive electrode active material of Comparative Example 2-1 was Li 3.3 Al 0.9 It was confirmed that it contained F6. That is, the coating portion of the positive electrode active material of Comparative Example 2-1 contained Li, which has chemical formula 1. 3+x Al [1-(1 / 3)x-y] Ga y In F6, it was found that gallium was not present, x was 0.3, and y was 0.

[0114] Comparative Example 2-2. Manufacturing of All-Solid-State Batteries A solid-state battery of Comparative Example 2-2 was manufactured in the same manner as in Example 1-2, except that the positive electrode active material of Comparative Example 2-1 was used.

[0115] <Manufacturing of a positive electrode active material in which the coating portion of the positive electrode active material contains a compound represented by chemical formula 2, and an all-solid-state battery containing the same> Example 5-1. Production of positive electrode active material for all-solid-state batteries CH3COOLi·2H2O, Ga(NO3)3·xH2O, and NH4F were added to anhydrous ethanol solvent in a molar ratio of 2.4:1.2:6 to disperse the precursors. 2.4925 g of NCM811 was added to the dispersion, and the mixture was heated at 90°C for 2 hours while stirring at 200 rpm to evaporate the anhydrous ethanol solvent.

[0116] Subsequently, the material was dried at 90°C for 2 hours, and then heated at a rate of 5°C / minute while injecting argon gas, resulting in a calcination treatment at 250°C for 2 hours. After cooling to room temperature, it was pulverized to produce the cathode 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] It contains the F6 compound.

[0118] ICP analysis of the aforementioned coating portion revealed that the coating portion of the positive electrode active material in Example 5-1 was Li 2.4 Ga 1.2 It was confirmed that it contains F6. That is, the coating portion of the positive electrode active material in Example 5-1 contains Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] At F6, it was found that z is -0.6.

[0119] Example 5-2. Manufacturing of an all-solid-state battery 100 mg of Li6PS5Cl was pressurized with a pressure of 2.5 tons to produce a solid electrolyte layer approximately 10 mm thick.

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

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

[0122] After stacking the positive electrode, solid electrolyte layer, negative electrode, and SUS current collector in that order, the assembly was pressurized with a pressure of 3.5 tons to produce the all-solid-state battery of Example 5-2.

[0123] Example 6-1. Production of positive electrode active material for all-solid-state batteries The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] It contains the F6 compound.

[0125] ICP analysis of the aforementioned coating portion revealed that the coating portion of the positive electrode active material in Example 6-1 was Li 2.7 Ga 1.1 It was confirmed that it contained F6. That is, the coating portion of the positive electrode active material in Example 6-1 is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] At F6, it was found that z is -0.3.

[0126] Example 6-2. Manufacturing of an all-solid-state battery The all-solid-state battery of Example 6-2 was manufactured 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 batteries The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z]It contains the F6 compound.

[0129] ICP analysis of the coating portion confirmed that the coating portion of the positive electrode active material in Example 7-1 contains Li3GaF6. In other words, the coating portion of the positive electrode active material in Example 7-1 contains Li3GaF6, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, it was found that z is 0.

[0130] Example 7-2. Manufacturing of an all-solid-state battery The all-solid-state battery of Example 7-2 was manufactured 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 batteries The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] It contains the F6 compound.

[0133] ICP analysis of the coating portion revealed that the coating portion of the positive electrode active material in Example 8-1 was Li 3.3 Ga 0.9 It was confirmed that it contains F6. That is, the coating portion of the positive electrode active material in Example 8-1 contains Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, it was found that z is 0.3.

[0134] Example 8-2. Manufacturing of an all-solid-state battery The all-solid-state battery of Example 8-2 was manufactured 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 The positive electrode active material was produced 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 NCM811 and the coating portion being Li 3+z Al [1-(1 / 3)z] It contains the F6 compound.

[0137] ICP analysis of the coating portion confirmed that the coating portion of the positive electrode active material of Comparative Example 3-1 contained Li3AlF6. In other words, the coating portion of the positive electrode active material of Comparative Example 3-1 contained Li3AlF6, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, aluminum is included instead of gallium.

[0138] Comparative Example 3-2. Manufacturing of All-Solid-State Batteries A solid-state battery of Comparative Example 3-2 was manufactured 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 The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] It contains the F6 compound.

[0141] As a result of ICP analysis of the aforementioned coating portion, the coating portion of the positive electrode active material of Comparative Example 4-1 was Li 3.45 Ga0.85 It was confirmed that it contained F6. That is, the coating portion of the positive electrode active material of Comparative Example 4-1 contains Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, it was found that z is 0.45.

[0142] Comparative Example 4-2. Manufacturing of All-Solid-State Batteries A solid-state battery of Comparative Example 4-2 was manufactured 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 The positive electrode active material was produced 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 is NCM811, and the coating portion is Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] It contains the F6 compound.

[0145] As a result of ICP analysis of the aforementioned coating portion, the coating portion of the positive electrode active material of Comparative Example 5-1 was Li 3.6 Ga 0.8 It was confirmed that it contained F6. That is, the coating portion of the positive electrode active material of Comparative Example 5-1 contained Li, which has chemical formula 2. 3+z Ga [1-(1 / 3)z] In F6, it was found that z is 0.6.

[0146] Comparative Example 5-2. Manufacturing of All-Solid-State Batteries A solid-state battery of Comparative Example 5-2 was manufactured 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 the ionic conductivity of the coating portion of the positive electrode active material. The ionic conductivity of the coating portion 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 the frequency range of 5.0 MHz to 7.0 MHz with an alternating current (AC) voltage applied at 10 mV using a symmetric cell composed of a solid electrolyte (Li6PS5Cl) / ion 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, the ionic conductivity of the coating portion of the positive electrode active material in Comparative Example 2-1, where y is outside the above range and does not contain gallium, showed a very low result, indicating that the effect of improving the ionic conductivity cannot be obtained.

[0153]

Table 2

[0154] In Examples 5-1 to 8-1, the coated portion is Li 2.4 Ga 1.2 F6, Li 2.7 Ga 1.1 F6, Li3GaF6 and Li 3.3 Al 0.9 It contains F6 and satisfies the range of z in the above chemical formula 2. On the other hand, in Comparative Examples 3-1 to 5-1, the coating portion is Li3AlF6, Li 3.45 Ga 0.85 F6 and Li 3.6 Ga 0.8 This includes compounds containing F6, those in chemical formula 2 that contain aluminum instead of gallium, and those where x exceeds 0.3, which falls outside the range of x in chemical formula 2.

[0155] From the results above, 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 falls outside the above range, the ionic conductivity of the coating portion is very low, indicating that no improvement in ionic conductivity is obtained.

[0156] Experimental Example 2. Measurement of the potential stabilization window of the coating portion of the positive electrode active material. The electrochemical stability of the coated portion of the positive electrode active material produced in Examples 2-1 to 3-1 and Comparative Examples 1-1 to 2-1 was measured.

[0157] Electrochemical stability was measured using the Linear Sweep Voltammetry (LSV) method with a biologic electrochemical instrument from 0V to 5V at a speed of 1.0mV / s, 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 in Chemical Formula 1, when 0 ≦ x ≦ 0.3, 0 < y < 1, and 0 < (1 / 3)x + y < 1 are satisfied, 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 electrochemical stability of the coating part of the positive electrode active material in Comparative Example 1-1 that does not contain aluminum shows a very low result, and it was found from this 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 is excellent in both 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 charge-discharge characteristic measurement, 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 in Tables 4 and 6, the positive electrode active material contained in the all-solid-state batteries of Examples 2-2 and 3-2 exhibited superior ionic conductivity and electrochemical stability compared to the positive electrode active material contained in the all-solid-state batteries of Comparative Examples 1-2 and 2-2. As a result, 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, the results from Tables 5 and 7 show that the positive electrode active material contained in the all-solid-state batteries of Examples 5-2 and 6-2 has superior ionic conductivity compared to the positive electrode active material contained in the all-solid-state batteries of Comparative Examples 4-2 and 5-2. As a result, the all-solid-state batteries of Examples 5-2 and 6-2 showed improved initial charge / discharge capacity and life characteristics compared to the all-solid-state batteries of Comparative Examples 4-2 and 5-2.

Claims

1. Core portion containing lithium metal oxide; and A positive electrode active material for an all-solid-state battery, comprising: a coating portion located on the 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 above x is 0 ≤ x ≤ 0.3, The above y is 0 < y < 1, (1 / 3)x + y is such that 0 < (1 / 3)x + y < 1, [Chemical formula 2] Li ３＋ｚ Ga ［１－（１／３）ｚ］ F ６ The above z is -0.6 ≤ z ≤ 0.

3.

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

9.

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

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

5. 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 below is included 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 portion.

6. The ionic conductivity of the compound represented by the above chemical formula 1 is 9 × 10 －６ It is S / cm or higher, The ionic conductivity of the compound represented by the chemical formula 2 is 8×10 －７ S / cm or more. The positive electrode active material for all-solid-state batteries according to claim 1.

7. (1) A step of mixing a lithium precursor, an aluminum precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to produce a mixture, or a step of mixing a lithium precursor, a gallium precursor, a fluorine precursor, and a lithium metal oxide to produce a mixture; (2) The step of heating and drying the mixture; and (3) A method for producing a positive electrode active material for an all-solid-state battery according to any one of claims 1 to 6, comprising the step of calcining the heated and dried mixture.

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

6.

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

6.

10. The method for producing a positive electrode active material for an all-solid-state battery according to claim 7, wherein the firing treatment is carried out 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 more and 5 hours or less.

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

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

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

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

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