Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0407—Methods of deposition of the material by coating on an electrolyte layer
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/362—Composites
  • H01M4/366—Composites as layered products
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
  • H01M2300/0071—Oxides
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• lithium-containing transition metal oxides having a layered rock salt structure when the ratio of the amount of substance of Ni to the total amount of substance of cations other than lithium is high, the charge/discharge capacity per unit weight becomes large.
• the ratio of the amount of substance of Ni to the total amount of substance of cations other than Li is, for example, 0.6 or more.
• the upper limit of the ratio of the amount of substance of Ni to the total amount of substance of cations other than Li is, for example, 0.95.
• the positive electrode active material 100 has, for example, a particle shape.
• the particle shape of the positive electrode active material 100 is not particularly limited.
• the particle shape of the positive electrode active material 100 can be spherical, oval spherical, scaly, or fibrous.
• the median diameter of the positive electrode active material 100 may be 0.1 ⁇ m or more and 100 ⁇ m or less.
• the median diameter of the positive electrode active material 100 is 0.1 ⁇ m or more, the positive electrode active material 100, the first solid electrolyte 101, and the second solid electrolyte 102 can form a good dispersion state in the positive electrode material 10. As a result, the charge and discharge characteristics of the battery are improved.
• the median diameter of the positive electrode active material 100 is 100 ⁇ m or less, the diffusion speed of lithium inside the positive electrode active material 100 is sufficiently ensured. Therefore, the battery can operate at high output.
• the median diameter of the positive electrode active material 100 may be larger than the median diameter of the second solid electrolyte 102. This allows the positive electrode active material 100 and the second solid electrolyte 102 to form a good dispersion state.
• volume diameter refers to the particle size when the cumulative volume in the volume-based particle size distribution is equal to 50%.
• the volume-based particle size distribution is measured, for example, by a laser diffraction measuring device or an image analyzer.
• the first solid electrolyte 101 has ion conductivity.
• the ion conductivity is typically lithium ion conductivity.
• the raw materials of the first solid electrolyte 101, by-products generated when producing the first solid electrolyte 101, and the like are included in the inevitable impurities.
• the ratio of the mass of the inevitable impurities to the total mass of the first solid electrolyte 101 may be 5% or less, 3% or less, 1% or less, or 0.5% or less.
• the first solid electrolyte 101 is a material that contains Li, Al, and X, but does not contain Ti. X is as described above. Such a material has excellent ionic conductivity and oxidation resistance. Therefore, the positive electrode material 10 that contains the first solid electrolyte 101 improves the charge/discharge efficiency and thermal stability of the battery.
• Ti-free material means a material synthesized without actively using Ti as a raw material.
• the first solid electrolyte 101 may contain at least one element selected from the group consisting of metal elements and semi-metal elements other than Li, Ti, and Al. By replacing Al with a different element, various effects such as improved lithium ion conductivity and improved mechanical properties can be expected.
• “Semi-metallic elements” are B, Si, Ge, As, Sb, and Te.
• Metallic elements are all elements in groups 1 to 12 of the periodic table (excluding hydrogen) and all elements in groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).
• metallic elements are a group of elements that can become cations when forming inorganic compounds with halogen elements.
• the first solid electrolyte 101 may contain at least one selected from the group consisting of Zr, Y, Ca, and Mg. By containing such an element, the first solid electrolyte 101 exhibits high lithium ion conductivity.
• the first solid electrolyte 101 has a composition formula (1): Li 6- ⁇ y (M 1-x Al x ) y F 6 ...(1) (wherein M is at least one element selected from the group consisting of metal elements and semimetal elements other than Ti and Al, ⁇ is the average valence of (M 1-x Al x ), and 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1.5 are satisfied).
• Halide solid electrolytes containing the phase represented by formula (1) have higher ionic conductivity than halides such as LiF, which are composed only of Li and halogen elements. Therefore, when a battery contains a halide solid electrolyte containing the phase represented by formula (1), the charge/discharge efficiency of the battery can be improved.
• the first solid electrolyte 101 may consist essentially of Li, Al, and X.
• “the first solid electrolyte 101 consists essentially of Li, Al, and X” means that the molar ratio (i.e., molar fraction) of the total amount of substance of Li, Al, and X to the total amount of substance of all elements constituting the first solid electrolyte 101 is 90% or more.
• the molar ratio (i.e., molar fraction) may be 95% or more.
• the first solid electrolyte 101 may consist only of Li, Al, and X, excluding inevitable impurities.
• the ratio of the amount of substance of F to the total amount of substance of the anions constituting the first solid electrolyte 101 may be 0.5 or more and 1.0 or less. With such a configuration, the oxidation resistance of the first solid electrolyte 101 is improved. The ratio may be 1.0. In other words, the anion may be only F. With such a configuration, it is expected that the first solid electrolyte 101 will have higher oxidation resistance.
• the ratio of the amount of Li to the amount of cations other than Li may be 1.5 or more and 6.0 or less. With this configuration, the lithium ion conductivity of the first solid electrolyte 101 can be improved.
• the first solid electrolyte 101 may be crystalline or amorphous.
• the shape of the first solid electrolyte 101 is, for example, needle-like, spherical, or elliptical.
• the first solid electrolyte 101 may be particles.
• the first solid electrolyte 101 may have a median diameter of 0.001 ⁇ m or more and 100 ⁇ m or less.
• the median diameter means the particle size when the cumulative volume in the volume-based particle size distribution is equal to 50%.
• the volume-based particle size distribution is measured, for example, by a laser diffraction measuring device or an image analyzer.
• the first solid electrolyte 101 forms a coating layer 104 that coats the surface of the positive electrode active material 100.
• the thickness of the coating layer 104 is, for example, 1 nm or more and 500 nm or less. If the thickness of the coating layer 104 is appropriately adjusted, contact between the positive electrode active material 100 and the second solid electrolyte 102 can be sufficiently suppressed.
• the thickness of the coating layer 104 can be determined by slicing the coated active material by a method such as ion milling and observing the cross section of the coated active material with an electron microscope. The average value of thicknesses measured at any number of positions (for example, five points) can be regarded as the thickness of the coating layer 104.
• the first solid electrolyte 101 may be a solid electrolyte that does not contain sulfur. In this case, it is possible to prevent the generation of sulfur-containing gases such as hydrogen sulfide gas from the solid electrolyte.
• a solid electrolyte that does not contain sulfur means a solid electrolyte that is expressed by a composition formula that does not contain elemental sulfur. Therefore, a solid electrolyte that contains a very small amount of sulfur, for example a solid electrolyte with a sulfur content of 0.1 mass% or less, belongs to the solid electrolyte that does not contain sulfur.
• the first solid electrolyte 101 may further contain oxygen as an anion other than halogen elements.
• the halide solid electrolyte as the first solid electrolyte 101 can be produced, for example, by the following method.
• Raw material powders are prepared and mixed to obtain the desired composition.
• the raw material powders may be, for example, halides.
• the target composition is Li 3 AlF 6
• LiF and AlF 3 are mixed in a molar ratio of about 3: 1.
• the raw material powders may be mixed in a pre-adjusted molar ratio to offset composition changes that may occur in the synthesis process.
• the raw powders are reacted with each other mechanochemically (i.e., using a mechanochemical milling method) in a mixing device such as a planetary ball mill to obtain a reactant.
• the reactant may be fired in a vacuum or in an inert atmosphere.
• a mixture of the raw powders may be fired in a vacuum or in an inert atmosphere to obtain a reactant.
• the firing is preferably carried out, for example, at a temperature of 100°C or higher and 400°C or lower for at least one hour.
• the raw powders are preferably fired in a closed container such as a quartz tube.
• the second solid electrolyte 102 may include at least one selected from the group consisting of a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte.
• halide solid electrolyte examples include the materials previously described as the first solid electrolyte 101.
• the composition of the second solid electrolyte 102 may be the same as or different from the composition of the first solid electrolyte 101.
• the oxide solid electrolyte is a solid electrolyte that contains oxygen.
• the oxide solid electrolyte may further contain anions other than sulfur and halogen elements as anions other than oxygen.
• oxide solid electrolytes examples include NASICON-type solid electrolytes such as LiTi2 ( PO4 ) 3 and its elemental substitution products, perovskite-type solid electrolytes such as ( LaLi)TiO3, LISICON-type solid electrolytes such as Li14ZnGe4O16, Li4SiO4 , LiGeO4 and their elemental substitution products, garnet-type solid electrolytes such as Li7La3Zr2O12 and its elemental substitution products , Li3PO4 and its N-substitution products, and glasses or glass ceramics containing a base material containing Li- B - O compounds such as LiBO2 and Li3BO3 to which materials such as Li2SO4 and Li2CO3 have been added.
• NASICON-type solid electrolytes such as LiTi2 ( PO4 ) 3 and its elemental substitution products
• perovskite-type solid electrolytes such as ( LaLi)TiO3, LISICON-type solid electrolytes such as Li14
• a compound of a polymer compound and a lithium salt can be used.
• the polymer compound may have an ethylene oxide structure.
• the polymer compound having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ion conductivity can be further increased.
• the lithium salt include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN (SO 2 CF 3 ) 2 , LiN (SO 2 C 2 F 5 ) 2 , LiN (SO 2 CF 3 ) (SO 2 C 4 F 9 ), and LiC (SO 2 CF 3 ) 3 .
• One type of lithium salt selected from these may be used alone, or a mixture of two or more types of lithium salts selected from these may be used.
• the second solid electrolyte 102 may contain Li and S.
• the second solid electrolyte 102 may contain a sulfide solid electrolyte.
• the sulfide solid electrolyte has high ionic conductivity and can improve the charge/discharge efficiency of the battery.
• the sulfide solid electrolyte may have poor oxidation resistance.
• Li2S - P2S5 Li2S - SiS2 , Li2S - B2S3 , Li2S - GeS2 , Li3.25Ge0.25P0.75S4 , Li10GeP2S12 , etc.
• LiX, Li2O , MOq , LipMOq , etc. may be added to these.
• X in “LiX” is at least one selected from the group consisting of F, Cl , Br , and I.
• the element M in “ MOq " and " LipMOq " is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. In “MO q “ and " Lip MO q ", p and q are each independent natural numbers.
• the second solid electrolyte 102 may contain two or more materials selected from the materials listed as solid electrolytes.
• the second solid electrolyte 102 may contain, for example, a halide solid electrolyte and a sulfide solid electrolyte.
• the second solid electrolyte 102 may have a lithium ion conductivity higher than the lithium ion conductivity of the first solid electrolyte 101.
• One selected from these may be used alone, or two or more may be used in combination.
• the binder may be an elastomer because of its excellent binding properties.
• An elastomer is a polymer that has rubber elasticity.
• the elastomer used as the binder may be a thermoplastic elastomer or a thermosetting elastomer.
• the binder may contain a thermoplastic elastomer.
• thermoplastic elastomers examples include styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), butylene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), styrene-butylene rubber (SBR), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), hydrogenated isoprene rubber (HIR), hydrogenated butyl rubber (HIIR), hydrogenated nitrile rubber (HNBR), hydrogenated styrene-butylene rubber (HSBR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), etc.
• the positive electrode material 10 may contain a conductive additive for the purpose of increasing electronic conductivity.
• conductive additives include graphites such as natural graphite and artificial graphite; carbon blacks such as acetylene black and ketjen black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride and aluminum; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene.
• the positive electrode active material 100 can be covered with the first solid electrolyte 101 by the following method.
• a powder of the positive electrode active material 100 and a powder of the first solid electrolyte 101 are mixed in an appropriate ratio to obtain a mixture.
• the mixture is milled to impart mechanical energy to the mixture.
• a mixing device such as a ball mill can be used for the milling process.
• the milling process may be performed in a dry and inert atmosphere to suppress oxidation of the materials.
• the positive electrode active material 100 coated with the first solid electrolyte 101 may be manufactured by a dry particle composite method.
• the treatment by the dry particle composite method includes applying at least one mechanical energy selected from the group consisting of impact, compression, and shear to the positive electrode active material 100 and the first solid electrolyte 101.
• the positive electrode active material 100 and the first solid electrolyte 101 are mixed in an appropriate ratio.
• the device used in the manufacture of the positive electrode active material 100 coated with the first solid electrolyte 101 is not particularly limited, and may be a device capable of imparting mechanical energy of impact, compression, and shear to the mixture of the positive electrode active material 100 and the first solid electrolyte 101.
• Devices capable of imparting mechanical energy include ball mills, and compression shear processing devices (particle composite devices) such as "Mechanofusion” (manufactured by Hosokawa Micron Corporation) and "Nobilta” (manufactured by Hosokawa Micron Corporation).
• Mechanism is a particle compounding device that uses a dry mechanical compounding technology by applying strong mechanical energy to multiple different raw material powders.
• mechanofusion the raw material powders fed between a rotating container and a press head are subjected to compression, shear, and friction mechanical energy. This causes the particles to compound.
• Nobilta is a particle compounding device that uses dry mechanical compounding technology, an advanced form of particle compounding technology, to compound nanoparticles as raw materials. Nobilta produces composite particles by applying mechanical energy in the form of impact, compression, and shear to multiple types of raw powders.
• Nobilta a rotor arranged to have a specified gap between itself and the inner wall of a horizontal cylindrical mixing vessel rotates at high speed, and the process of forcing the raw material powder to pass through the gap is repeated multiple times. This applies impact, compression, and shear forces to the mixture, making it possible to produce composite particles of the positive electrode active material 100 and the first solid electrolyte 101.
• By adjusting conditions such as the rotor rotation speed, processing time, and loading amount it is possible to control the thickness of the first solid electrolyte 101, the coverage rate of the positive electrode active material 100 by the first solid electrolyte 101, and the like.
• the active material coated with the first solid electrolyte 101 may be produced by mixing the positive electrode active material 100 and the first solid electrolyte 101 using a mortar, mixer, or the like.
• the first solid electrolyte 101 may be deposited on the surface of the positive electrode active material 100 by various methods such as a spray method, a spray dry coating method, an electrodeposition method, an immersion method, or a mechanical mixing method using a disperser.
• Lithium-containing transition metal oxides with a layered rock salt structure tend to react more easily with water when the Ni ratio is high.
• a reaction layer is likely to form on the surface of the active material particles due to the reaction between the lithium-containing transition metal oxide and water.
• the reaction layer itself becomes a resistance layer during charging and discharging, leading to a decrease in battery performance. For this reason, when the Ni ratio is high, a coating method that does not use water is desirable. However, this is not a requirement.
• the positive electrode material 10 is obtained by mixing the positive electrode active material 100 coated with the first solid electrolyte 101 and the second solid electrolyte 102.
• the method of mixing the positive electrode active material 100 coated with the first solid electrolyte 101 and the second solid electrolyte 102 is not particularly limited.
• the positive electrode active material 100 coated with the first solid electrolyte 101 and the second solid electrolyte 102 may be mixed using an instrument such as a mortar, or the positive electrode active material 100 coated with the first solid electrolyte 101 and the second solid electrolyte 102 may be mixed using a mixing device such as a ball mill.
• the two may be mixed in a solvent using a mixing device such as a homogenizer.
• (Modification) 2 is a cross-sectional view showing a schematic configuration of a cathode material 20 according to a modified example.
• the cathode material 20 has a cathode active material 100, a coating layer 105, and a second solid electrolyte 102.
• the coating layer 105 includes a first solid electrolyte 101 and an undercoat material 103.
• the cathode active material 100 is coated with the undercoat material 103 and the first solid electrolyte 101 in this order.
• the coating layer 105 has a first portion including the undercoat material 103 and a second portion including the first solid electrolyte 101.
• the base material 103 may contain a material with low electronic conductivity, such as an oxide material or an oxide solid electrolyte.
• oxide materials include SiO2 , Al2O3 , TiO2 , B2O3 , Nb2O5 , WO3 , and ZrO2 .
• oxide solid electrolytes include Li-Nb-O compounds such as LiNbO 3 , Li-B-O compounds such as LiBO 2 and Li 3 BO 3 , Li-Al-O compounds such as LiAlO 2 , Li-Si-O compounds such as Li 4 SiO 4 , Li-S-O compounds such as Li 2 SO 4 , Li-Ti-O compounds such as Li 4 Ti 5 O 12 , Li-Zr-O compounds such as Li 2 ZrO 3 , Li-Mo-O compounds such as Li 2 MoO 3 , Li-V-O compounds such as LiV 2 O 5 , and Li-W-O compounds such as Li 2 WO 4.
• the undercoat material 103 may be one selected from these, or a mixture of two or more.
• the base material 103 may contain a solid electrolyte having lithium ion conductivity.
• the base material 103 is typically an oxide solid electrolyte having lithium ion conductivity.
• the oxide solid electrolyte has high ion conductivity and is excellent in high potential stability. By using an oxide solid electrolyte as the base material 103, the charge/discharge efficiency of the battery can be improved.
• the underlayer material 103 may be a material containing Nb. Typically, the underlayer material 103 contains lithium niobate (LiNbO 3 ). With this configuration, the charge/discharge efficiency of the battery can be improved. As the oxide solid electrolyte that is the underlayer material 103, the oxide solid electrolyte described above can also be used.
• the thickness of the first portion including the base material 103 is, for example, 1 nm or more and 500 nm or less.
• the thickness of the first portion including the base material 103 is appropriately adjusted, contact between the positive electrode active material 100 and the second solid electrolyte 102 can be sufficiently suppressed.
• the method for forming the coating layer 105 on the surface of the positive electrode active material 100 is not particularly limited. After forming the first portion including the base material 103, the second portion including the first solid electrolyte 101 can be formed by the method described above. Methods for forming the first portion including the base material 103 include a liquid phase coating method and a gas phase coating method.
• a precursor solution of the underlayer material 103 is applied to the surface of the positive electrode active material 100.
• the precursor solution can be a mixed solution (sol solution) of a solvent, lithium alkoxide, and niobium alkoxide.
• the lithium alkoxide can be lithium ethoxide.
• the niobium alkoxide can be niobium ethoxide.
• the solvent can be, for example, an alcohol such as ethanol.
• the amount of lithium alkoxide and niobium alkoxide is adjusted according to the target composition of the underlayer material 103. Water may be added to the precursor solution as necessary.
• the precursor solution may be acidic or alkaline.
• the method of applying the precursor solution to the surface of the positive electrode active material 100 is not particularly limited.
• the precursor solution can be applied to the surface of the positive electrode active material 100 using a tumbling fluidized granulation coating device.
• the precursor solution can be sprayed onto the positive electrode active material 100 while the positive electrode active material 100 is tumbling and fluidized, and the precursor solution can be applied to the surface of the positive electrode active material 100.
• a precursor coating is formed on the surface of the positive electrode active material 100.
• the positive electrode active material 100 coated with the precursor coating is then heat-treated. The gelation of the precursor coating proceeds through the heat treatment, and a first portion including the base material 103 is formed.
• Examples of the vapor-phase coating method include a pulsed laser deposition (PLD) method, a vacuum deposition method, a sputtering method, a thermal chemical vapor deposition (CVD) method, and a plasma chemical vapor deposition method.
• PLD pulsed laser deposition
• a vacuum deposition method e.g., a vacuum deposition method
• a sputtering method e.g., a thermal chemical vapor deposition (CVD) method
• a plasma chemical vapor deposition method e.g., a plasma chemical vapor deposition method.
• a pulsed laser with high energy e.g., a KrF excimer laser, wavelength: 248 nm
• the sublimated ion-conductive material is deposited on the surface of the positive electrode active material 100.
• a highly densely sintered LiNbO 3 is used as a target.
• the method of forming the first portion including the base material 103 is not limited to the above.
• the first portion including the base material 103 may be formed by various methods such as a spray method, a spray dry coating method, an electrodeposition method, a dipping method, or a mechanical mixing method using a disperser.
• (Embodiment 2) 3 is a cross-sectional view showing a schematic configuration of a battery according to embodiment 2.
• Battery 200 includes a positive electrode 201, a separator layer 202, and a negative electrode 203. Separator layer 202 is disposed between positive electrode 201 and negative electrode 203.
• Positive electrode 201 includes at least one of positive electrode material 10 and positive electrode material 20 described in embodiment 1. According to this embodiment, it is possible to provide positive electrode 201 having excellent resistance to deterioration and battery 200 having the same.
• each of the positive electrode 201 and the negative electrode 203 may be 10 ⁇ m or more and 500 ⁇ m or less. If the thickness of the positive electrode 201 and the negative electrode 203 is 10 ⁇ m or more, sufficient energy density of the battery can be ensured. If the thickness of the positive electrode 201 and the negative electrode 203 is 500 ⁇ m or less, high-power operation of the battery 200 can be achieved.
• the separator layer 202 is a layer containing an electrolyte material.
• the separator layer 202 may contain at least one solid electrolyte selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte. Details of each solid electrolyte are as described in the first embodiment.
• the thickness of the separator layer 202 may be 1 ⁇ m or more and 300 ⁇ m or less. When the thickness of the separator layer 202 is 1 ⁇ m or more, the positive electrode 201 and the negative electrode 203 can be more reliably separated. When the thickness of the separator layer 202 is 300 ⁇ m or less, the battery 200 can be operated at high output.
• the negative electrode 203 contains a material as the negative electrode active material that has the property of absorbing and releasing metal ions (e.g., lithium ions).
• metal ions e.g., lithium ions
• metal materials, carbon materials, oxides, nitrides, tin compounds, silicon compounds, etc. can be used as the negative electrode active material.
• the metal material may be a single metal.
• the metal material may be an alloy.
• Examples of the metal material include lithium metal and lithium alloys.
• Examples of the carbon material include natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. From the viewpoint of capacity density, silicon (Si), tin (Sn), silicon compounds, tin compounds, etc. can be preferably used.
• the median diameter of the particles of the negative electrode active material may be 0.1 ⁇ m or more and 100 ⁇ m or less.
• the negative electrode 203 may contain other materials, such as a solid electrolyte.
• the material described in embodiment 1 can be used as the solid electrolyte.
• a positive electrode active material A coating layer including a first solid electrolyte and coating at least a portion of a surface of the positive electrode active material;
• a second solid electrolyte; Equipped with The first solid electrolyte contains Li, Al, and X, and does not contain Ti;
• X is at least one selected from the group consisting of F, Cl, Br, and I;
• a ratio of the volume of the first solid electrolyte to the total volume of the first solid electrolyte and the second solid electrolyte is 1.0% or more and 25.0% or less; Positive electrode material.
• This configuration improves the battery's resistance to deterioration due to charge/discharge cycles.
• the first solid electrolyte has a composition formula (1): Li 6- ⁇ y (M 1-x Al x ) y F 6 ...(1) (wherein M is at least one element selected from the group consisting of metal elements and semimetal elements other than Ti and Al, and ⁇ is the average valence of (M 1-x Al x ), where 0 ⁇ x ⁇ 1 and 0 ⁇ y ⁇ 1.5 are satisfied).
• a halide solid electrolyte containing a phase represented by composition formula (1) has a higher ionic conductivity than a halide such as LiF consisting only of Li and a halogen element.
• the present disclosure provides a positive electrode with excellent resistance to deterioration and a battery having the same.
• Example 1 Preparation of first solid electrolyte
• These raw material powders were charged into a 45cc planetary ball mill pod together with a 1mm ⁇ ball (25g).
• ⁇ -butyrolactone (GBL) was dripped into the pod so that the solid content ratio was 30%.
• the solid content ratio is calculated by ⁇ (mass of input raw materials)/(mass of input raw materials + mass of input solvent) ⁇ x 100.
• milling was performed for 12 hours at 500 rpm.
• the balls were separated to obtain a slurry.
• the obtained slurry was dried at 270°C for 1 hour under nitrogen flow using a mantle heater.
• the obtained solid was crushed in a mortar to obtain a powder of the halide solid electrolyte according to Example 1.
• the halide solid electrolyte according to Example 1 had a composition represented by Li 3 AlF 6 (hereinafter referred to as LAF).
• NCA Li(Ni,Co,Al) O2
• a coating layer made of LAF was formed on the surface of the NCA.
• the coating layer was formed by a compression shear treatment using a particle composite device (NOB-MINI, manufactured by Hosokawa Micron Corporation). Specifically, the NCA and LAF were weighed to have a volume ratio of 98.9:1.1, and treated under the conditions of blade clearance: 2 mm, rotation speed: 8000 rpm, and treatment time: 30 min. As a result, the coated active material of Example 1 was obtained.
• Example 2 A coated active material of Example 2 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 96.9:3.1.
• a positive electrode material of Example 2 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 4.4:95.6.
• Example 3 A coated active material of Example 3 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 96.4:3.6.
• a positive electrode material of Example 3 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 5.1:94.9.
• Example 4 A coated active material of Example 4 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 95.9:4.1.
• a positive electrode material of Example 4 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 5.8:94.2.
• Example 5 A coated active material of Example 5 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 95.4:4.6.
• a positive electrode material of Example 5 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 6.6:93.4.
• Example 6 A coated active material of Example 6 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 94.4:5.6.
• a positive electrode material of Example 6 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 8.1:91.9.
• Example 7 A coated active material of Example 7 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 91.9:8.1.
• a positive electrode material of Example 7 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 12:88.
• Example 8 A coated active material of Example 8 was obtained in the same manner as in Example 1, except that the volume ratio of NCA to LAF was changed to 84.9:15.1.
• a positive electrode material of Example 8 was obtained in the same manner as in Example 1, except that the volume ratio of LAF to LPS was changed to 24.2:75.8.
• the ratio of the volume of LAF to the total volume of LAF and NCA was as shown in Table 1.
• the ratio of the volume of LAF to the total volume of LAF and LPS was as shown in Table 1.
• a positive electrode material, a binder, a solvent, and a conductive assistant were mixed in an argon glove box with a dew point of ⁇ 60° C. or less, and dispersed using a homogenizer to prepare a slurry of the positive electrode material.
• the slurry was applied onto a current collector and dried on a hot plate to prepare the positive electrodes of Examples 1 to 8 and Comparative Example 1.
• Lithium titanate (hereinafter referred to as LTO) was used as the negative electrode active material.
• LTO Lithium titanate
• an argon glove box with a dew point of -60°C or less a binder, a solvent, a conductive assistant, and LPS were mixed and dispersed using a homogenizer. This resulted in a mixture of the binder, the solvent, the conductive assistant, and LPS.
• LTO was added to the mixture, mixed, and dispersed using a homogenizer to prepare a slurry of the negative electrode material. The slurry was applied onto a current collector and dried on a hot plate to prepare a negative electrode.
• the mixing ratio of LTO and LPS was 65:35 by volume.
• the LPS, binder, and solvent were mixed and dispersed using a homogenizer. This produced a slurry containing LPS. The slurry was applied to a substrate and dried on a hot plate to produce an electrolyte layer.
• the negative electrode and the electrolyte layer were laminated and pressure molded while being heated, and then the base material was removed from the electrolyte layer.
• the positive electrode was laminated on the electrolyte layer so that the electrolyte layer was disposed between the positive electrode and the negative electrode, and pressure molded while being heated. After attaching a current collecting lead to the obtained molded body, it was placed in a laminate packaging material and the packaging material was sealed. In this way, the batteries of Examples 1 to 8 and Comparative Example 1 were produced.
• the battery was placed in a thermostatic chamber at 25°C. (i) The battery was charged at a constant current of 0.4mA, which corresponds to a 0.3C rate (3.3 hour rate) relative to the theoretical capacity of the battery, to a voltage of 2.7V, and then charged at a constant voltage of 2.7V, and charging was terminated at a current value of 0.013mA, which corresponds to a 0.01C rate. Thereafter, the battery was discharged at a constant current of 0.3C to a voltage of 1.5V, and the initial value of the 0.3C discharge capacity was measured.
• the battery was again charged at a constant current of 0.3C to a voltage of 2.7V, and then charged at a constant voltage of 2.7V, and charging was terminated at a current value of 0.013mA, which corresponds to a 0.01C rate. Thereafter, the battery was discharged at a constant current of 6.7mA, which corresponds to a 5C rate, to a voltage of 1.5V, and the initial value of the 5C discharge capacity was measured.
• the temperature of the thermostatic chamber was again set to 25°C, and evaluations (i), (ii), and (iii) were carried out.
• the ratio (%) of the 5C discharge capacity after cycling to the 0.3C discharge capacity after cycling was calculated.
• the calculation results are shown in Table 1 as "5C/0.3C discharge capacity ratio (%) after cycling.”
• “5C/0.3C discharge capacity ratio (%) after cycling” is expressed as the ratio (%) of the 5C/0.3C discharge capacity ratio after cycling to the 5C/0.3C discharge capacity ratio before cycling.
• the arc resistance was reduced.
• the output characteristics of the battery were improved.
• the rate of increase in the arc resistance due to charge/discharge cycles was also significantly reduced.
• the reaction between the oxygen released from the positive electrode active material and the sulfide solid electrolyte was suppressed, suggesting that this improves the initial output characteristics as well as resistance to deterioration due to charge/discharge cycles.
• the 5C/0.3C discharge capacity ratio increased by covering the positive electrode active material with a halide solid electrolyte. Furthermore, the rate of decrease in the discharge capacity ratio due to charge/discharge cycles was also significantly reduced. In other words, the reaction between the oxygen released from the positive electrode active material and the sulfide solid electrolyte was suppressed.
• the effect of suppressing the reaction between the positive electrode active material and the sulfide solid electrolyte is believed to be due to the high oxidation resistance of the halide solid electrolyte. From the standpoint of oxidation resistance, fluorine is believed to be the most excellent, but even if some or all of the fluorine is replaced with another halogen element, the halide solid electrolyte will achieve the same effect as that obtained in this example.
• the halide solid electrolyte contains a metal or semimetal element other than Al, the halide solid electrolyte will have the same effect as that obtained in this embodiment.
• the effect of suppressing the reaction between the positive electrode active material and the sulfide solid electrolyte is due to the high oxidation resistance of the halide solid electrolyte being attributed to the high electronegativity of the halogen element.
• results shown in this example are believed to be obtainable when using a positive electrode active material other than NCA, particularly a lithium-containing transition metal oxide.
• the effect of suppressing the reaction between the oxygen released from the lithium-containing transition metal oxide and the sulfide solid electrolyte is believed to be obtainable regardless of the composition of the positive electrode active material.
• results shown in this example are expected to be obtained when a sulfide solid electrolyte other than LPS is used as the second solid electrolyte. This is because sulfide solid electrolytes other than LPS also tend to have poor oxidation resistance, just like LPS.
• the technology disclosed herein is useful for solid-state batteries.
• Positive electrode material 100 Positive electrode active material 101 First solid electrolyte 102 Second solid electrolyte 103 Base material 104, 105 Covering layer 200 Battery 201 Positive electrode 202 Separator layer 203 Negative electrode

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