WO2023238580A1 - 被覆活物質、それを用いた電池、および、被覆活物質の製造方法 - Google Patents

被覆活物質、それを用いた電池、および、被覆活物質の製造方法 Download PDF

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WO2023238580A1
WO2023238580A1 PCT/JP2023/017471 JP2023017471W WO2023238580A1 WO 2023238580 A1 WO2023238580 A1 WO 2023238580A1 JP 2023017471 W JP2023017471 W JP 2023017471W WO 2023238580 A1 WO2023238580 A1 WO 2023238580A1
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active material
positive electrode
coated active
coated
carbon
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French (fr)
Japanese (ja)
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健太 長嶺
賢治 長尾
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Toyota Motor Corp
Panasonic Holdings Corp
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Toyota Motor Corp
Panasonic Holdings Corp
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Priority to JP2024526311A priority Critical patent/JPWO2023238580A1/ja
Priority to CN202380044688.0A priority patent/CN119318033A/zh
Publication of WO2023238580A1 publication Critical patent/WO2023238580A1/ja
Priority to US18/974,067 priority patent/US20250105280A1/en
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    • 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
    • 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
    • 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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of 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
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • 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
    • H01M2300/008—Halides
    • 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

  • the present disclosure relates to a coated active material, a battery using the same, and a method for manufacturing the coated active material.
  • Patent Document 1 discloses a composite active material containing carbonaceous material.
  • Patent Document 2 discloses a coated positive electrode active material containing carbonate.
  • a positive electrode active material a coating material that covers at least a portion of the surface of the positive electrode active material;
  • a coated active material comprising:
  • the coating material includes a compound represented by the following compositional formula (1) and carbon attributed to a C1s peak having a binding energy of 288.5 ⁇ 1.5 eV,
  • a, b, and c are positive real numbers
  • M is at least one element other than Li and O
  • the atomic ratio X C of carbon and the atomic ratio X M satisfy the following formula (2), A coated active material is provided.
  • Li a M b O c ...(1) 0.29 ⁇ X C /(X M +X C )...(2)
  • the coated active material of the present disclosure it is possible to suppress an increase in battery resistance due to a durability test.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of a coated active material 130 in the first embodiment.
  • FIG. 2 is a cross-sectional view showing a schematic configuration of positive electrode material 1000 in Embodiment 2.
  • FIG. 3 is a cross-sectional view showing a schematic configuration of a battery 2000 in Embodiment 3.
  • FIG. 4 is a graph showing the relationship between X C /(X Nb +X C ) and initial resistance, and the relationship between X C /(X Nb + X C ) and resistance change rate.
  • FIG. 5 is a graph showing the elemental profile in the depth direction of the coated active material of Comparative Example 1.
  • FIG. 6 is a graph showing the elemental profile in the depth direction of the coated active material of Example 4.
  • FIG. 7 is a graph showing C1sXPS spectra of the coated active materials of Example 6 and Comparative Example 1.
  • a coating layer of an ion-conductive oxide such as lithium niobate on the surface of the active material.
  • the coating layer needs to be uniformly formed on the surface of the active material to a thickness that does not inhibit ion conduction, for example, from several nanometers to several hundred nanometers.
  • the active material is a particle with a size of several micrometers and has an uneven surface, there are limited methods for forming a coating layer on the surface.
  • One method is to form a coating layer by mixing an organometallic compound and an active material and firing the mixture.
  • Another method is to form a coating layer by drying the active material while spraying a solution containing metal ions onto the active material.
  • the thickness of the coating layer may be non-uniform, or there may be areas where the coating layer does not exist.
  • a vapor phase method such as a sputtering method
  • the thickness of the coating layer is insufficient and it is difficult to obtain a sufficient protective effect for the active material.
  • the present inventors have conducted extensive studies on the structure of an active material suitable for suppressing the increase in battery resistance caused by durability tests. As a result, the inventors discovered that by disposing a specific carbon compound on the surface of the active material, it was possible to suppress the increase in battery resistance caused by the durability test, and completed the coated active material of the present disclosure.
  • the term "endurance test” refers to a test in which charging and discharging are repeated at a high rate in a high temperature atmosphere, as explained in the Examples section.
  • the coated active material according to the first aspect of the present disclosure is: a positive electrode active material; a coating material that covers at least a portion of the surface of the positive electrode active material; A coated active material comprising:
  • the coating material includes a compound represented by the following compositional formula (1) and carbon attributed to a C1s peak having a binding energy of 288.5 ⁇ 1.5 eV,
  • a, b, and c are positive real numbers
  • M is at least one element other than Li and O
  • the atomic ratio X C of carbon and the atomic ratio X M of M satisfy the following formula (2). Li a M b O c ...(1) 0.29 ⁇ X C /(X M +X C )...(2)
  • the coated active material of the present disclosure it is possible to suppress an increase in battery resistance due to a durability test.
  • the atomic ratio X C and the atomic ratio X M may satisfy the relationship of formula (3) below. According to such a configuration, the effect of suppressing an increase in resistance is enhanced. 0.29 ⁇ X C /(X M +X C ) ⁇ 0.67...(3)
  • the carbon in the coated active material according to the first or second aspect, may be distributed in a region having a depth of 50 nm or less from the surface of the coated active material. According to such a configuration, the ionic conductivity of the coating material is less likely to be inhibited.
  • M is at least one element selected from the group consisting of metal elements and metalloid elements. It may be.
  • the M is in a trivalent state, a tetravalent state, a pentavalent state, or a state thereof. It may be in a mixed state. According to such a configuration, the ionic conductivity of the coating material can be improved, so that the resistance of the battery can be further reduced.
  • M may include niobium.
  • the coating material contains niobium, the lithium ion conductivity of the coating material can be improved.
  • M includes at least one selected from the group consisting of nitrogen, sulfur, and phosphorus. You can stay there. According to such a structure, the structure of the coating material becomes amorphous easily, and the lithium ion conductivity of the coating material improves.
  • the positive electrode active material includes a lithium-containing transition metal oxide having a layered rock salt structure. Good too. By using such a material, excellent charge/discharge characteristics can be achieved.
  • the battery according to the ninth aspect of the present disclosure includes: A positive electrode including a coated active material according to any one of the first to eighth aspects is provided.
  • the battery according to the tenth aspect of the present disclosure includes: A positive electrode comprising the coated active material according to any one of the first to eighth aspects; a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; Equipped with
  • the electrolyte layer may include a sulfide solid electrolyte. According to such a configuration, the charging and discharging efficiency of the battery can be further improved.
  • the method for producing a coated active material according to the twelfth aspect of the present disclosure includes: Coating the positive electrode active material with a coating material; Contacting the positive electrode active material coated with the coating material with a processing gas containing carbon dioxide gas at a higher concentration than the atmosphere; including.
  • the concentration of carbon constituting carbonate ions in the surface layer of the positive electrode active material coated with the coating material can be increased.
  • the method for producing a coated active material according to the twelfth aspect may further include heating the positive electrode active material coated with the coating material while bringing it into contact with the processing gas. good. By heating, the concentration of carbon constituting carbonate ions in the surface layer of the positive electrode active material coated with the coating material can be efficiently increased.
  • the main component of the processing gas may be the carbon dioxide gas. If carbon dioxide gas is used, the concentration of carbonate ions in the surface layer of the positive electrode active material coated with the coating material can be efficiently increased.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of a coated active material 130 in the first embodiment.
  • Coated active material 130 includes positive electrode active material 110 and coating material 111.
  • Coating material 111 covers at least a portion of the surface of positive electrode active material 110 .
  • the shape of the positive electrode active material 110 is, for example, particulate.
  • the shape of the covering material 111 is, for example, layered.
  • the coating material 111 includes a compound represented by the following compositional formula (1) and carbon assigned to a C1s peak having a binding energy of 288.5 ⁇ 1.5 eV.
  • the C1s peak is a peak that appears in an XPS (X-ray Photoelectron Spectroscopy) spectrum.
  • the carbon assigned to the C1s peak having a binding energy of 288.5 ⁇ 1.5 eV is carbon that constitutes carbonate ion (CO 3 2 ⁇ ).
  • a, b, and c are positive real numbers, and M is at least one element other than Li and O.
  • the atomic ratio X C of carbon and the atomic ratio X M of M constituting carbonate ions satisfy the relationship of formula (2) below.
  • carbonate layer a layer containing carbon that constitutes carbonate ions is sometimes referred to as a "carbonate layer.”
  • Carbon constituting carbonate ions is present on the surface of the coated active material 130.
  • the coating material 111 contains carbon that constitutes carbonate ions. According to such a configuration, even if there is a defect that cannot be eliminated by the compound of formula (1) alone, or if there is a thin part of the compound of formula (1), the carbonate ion
  • the carbon constituting the positive electrode active material 110 can prevent contact between the positive electrode active material 110 and the solid electrolyte in the positive electrode. As a result, it is possible to suppress an increase in the resistance of the battery due to the durability test.
  • Carbon contained in organic matter, graphite, amorphous carbon, etc. does not have the above effects because it causes oxidative decomposition during battery operation and causes deterioration of the solid electrolyte due to electronic conductivity. .
  • the carbon constituting the carbonate ion may be insulating.
  • carbon constituting carbonate ions exists only between the positive electrode active material and the coating material, it is difficult to control the amount of carbon attached and the thickness of the region where carbon is distributed. Therefore, carbon may actually become a factor that inhibits ion conduction, or the protective performance of carbon may become insufficient.
  • lithium carbonate and/or lithium hydrogen carbonate exist as residual alkali components on the surface of a composite oxide containing lithium and a transition metal.
  • the protective performance of lithium carbonate and/or lithium hydrogen carbonate as the residual alkali component is not sufficient.
  • the ratio of Li 2 O--H 2 O--CO 2 can take any value. If the proportion of H 2 O is large, lithium hydrogen carbonate may be electrochemically or thermally decomposed and the battery characteristics may deteriorate.
  • Equation (2) which defines the lower limit of X C /(X M +X C ), is provided for the purpose of excluding carbon caused by carbon dioxide in the air.
  • the atomic ratio X C and the atomic ratio X M may satisfy the relationship of formula (3) below. According to such a configuration, the effect of suppressing an increase in resistance is enhanced.
  • the coating material 111 contains a suitable amount of carbon. Ionic conduction between the positive electrode active material 110 and the solid electrolyte in the positive electrode is also less likely to be inhibited, so an increase in resistance can be suppressed more effectively.
  • the value of X C /(X M +X C ) is in the range of 0.29 or more and less than 0.67, both the protective performance and ionic conductivity of the coating material 111 can be achieved.
  • the atomic ratio X C and the atomic ratio X M may satisfy the relationship of formula (4) below. According to such a configuration, the effect of suppressing an increase in resistance is further enhanced.
  • the atomic ratio X C and the atomic ratio X M may satisfy the relationship of formula (5) below. According to such a configuration, the effect of suppressing an increase in resistance is further enhanced.
  • the atomic ratio X C means the atomic ratio (unit: atomic %) of carbon constituting carbonate ions to all elements on the surface of the coated active material 130.
  • the atomic ratio X M means the atomic ratio (unit: atomic %) of the element M to all elements on the surface of the coated active material 130.
  • the term "surface” does not necessarily mean the outermost surface, but refers to a region with a thickness of several nm, which corresponds to the escape depth of photoelectrons in XPS measurements.
  • the atomic ratio X C of carbon and the atomic ratio X M of M constituting carbonate ions on the surface of the coated active material 130 can be determined using X-ray photoelectron spectroscopy (XPS).
  • the carbon atomic ratio X C can be calculated from the peak assigned to C1s.
  • the peak assigned to C1s appears in the binding energy range of 282 eV to 291 eV in the XPS spectrum.
  • a peak existing around 288.5 ⁇ 1.5 eV is a peak attributed to carbon having a bond originating from a carbonate ion.
  • a peak existing around 285 eV is a peak attributed to carbon having other bonds. Therefore, first, the atomic ratio of all carbons, X Ctot , is calculated based on the peak appearing in the binding energy range of 282 eV to 291 eV.
  • the peak attributed to carbon constituting the carbonate ion and the peak attributed to other carbons are separated.
  • the ratio of the area of the peak attributed to carbon constituting the carbonate ion to the total area of the C1s peak is represented by r C1
  • the atomic ratio X M of M can be measured in the range of binding energies typical of the elements included in the coating material 111, such as metals or metalloid elements.
  • the peak attributed to Nb3d exists in the binding energy range of 200 eV to 212 eV in the XPS spectrum.
  • the Nb atomic ratio X Nb can be calculated using the Nb3d peak.
  • the effect of charging in the XPS measurement may be corrected by specifying the peak located on the lowest binding energy side of C1s to 285 eV.
  • the carbon constituting the carbonate ions may be distributed in a region with a depth of 50 nm or less from the surface of the coated active material 130.
  • the thickness of the carbonate layer which is a layer containing carbon constituting carbonate ions, may be 50 nm or less from the surface of the coated active material 130 toward the inside.
  • the ionic conductivity of the coating material 111 is less likely to be inhibited. This contributes to reducing the resistance of the battery and suppressing an increase in resistance due to durability tests.
  • the thickness of the carbonate layer can be calculated as a SiO 2 equivalent thickness using etching conditions determined by argon etching of a SiO 2 thin film having a known thickness.
  • the peak existing around 285 eV is a peak derived from carbon having a C—C bond. Such carbon may originate from the oil of the vacuum pump used in XPS measurements, or may originate from the carbon tape used to fix the sample.
  • M in the compound Li a M b O c contained in the coating material 111 may be at least one element selected from the group consisting of metal elements and metalloid elements. According to such a configuration, the lithium ion conductivity of the coating material 111 can be improved, and the resistance of the battery can be reduced.
  • M in the compound Li a M b O c contained in the coating material 111 can be in a trivalent state, a tetravalent state, a pentavalent state, or a mixed state thereof. According to such a configuration, the ionic conductivity of the covering material 111 can be improved, so that the resistance of the battery can be further reduced.
  • the oxide ion contained in the coating material 111 and the multivalent ion M are more strongly bonded, so that the bond between the lithium ion and the oxide ion can be weakened. As a result, the lithium ion conductivity of the coating material 111 can be improved.
  • Examples of the compound contained in the coating material 111 include Li-Nb-O compounds such as LiNbO 3 , Li-B-O compounds such as LiBO 2 and Li 3 BO 3 , LiAlO 2 , Li-Si-O compounds such as Li 4 SiO 4 , Li-Ti-O compounds such as Li 2 SO 4 , Li 4 Ti 5 O 12 , Li-Ti-O compounds such as Li 2 ZrO 3 -Zr-O compounds, Li-Mo-O compounds such as Li 2 MoO 3 , Li-V-O compounds such as LiV 2 O 5 , Li-WO compounds such as Li 2 WO 4 , Li 3 PO 4 , etc.
  • Li-Nb-O compounds such as LiNbO 3
  • Li-B-O compounds such as LiBO 2 and Li 3 BO 3
  • LiAlO 2 Li-Si-O compounds such as Li 4 SiO 4
  • Li-Ti-O compounds such as Li 2 SO 4
  • Li 4 Ti 5 O 12 Li-Ti-O compounds
  • Li--P--O compounds such as Li--P--O compounds such as LiNO 3
  • Li-S--O compounds such as Li 2 SO 3 .
  • One type selected from these compounds may be used alone, or two or more types may be used in combination.
  • M in the compound represented by formula (1) may contain niobium. That is, the coating material 111 may contain a composite oxide of lithium and niobium. When the coating material 111 contains niobium, the lithium ion conductivity of the coating material 111 can be improved, and the resistance of the battery can be reduced.
  • M in the compound represented by formula (1) may contain at least one selected from the group consisting of nitrogen, sulfur, and phosphorus.
  • the compound represented by formula (1) is a Li-PO compound such as Li 3 PO 4 , a Li-N-O compound such as LiNO 3 , and a Li-S-O compound such as Li 2 SO 3 . It may contain at least one selected from the group consisting of compounds.
  • the coating material 111 contains at least one selected from the group consisting of nitrogen, sulfur, and phosphorus, the structure of the coating material 111 becomes amorphous easily, and the lithium ion conductivity of the coating material 111 improves. As a result, the resistance of the battery can be reduced.
  • the thickness of the layer containing the coating material 111 may be 0.1 nm or more and 100 nm or less.
  • the layer containing the coating material 111 has a thickness of 0.1 nm or more, direct contact between the positive electrode active material 110 and the solid electrolyte at the positive electrode of the battery is sufficiently suppressed, and side reactions of the solid electrolyte are suppressed. It can be done. As a result, the charging and discharging efficiency of the battery is improved.
  • the layer containing the coating material 111 has a thickness of 100 nm or less, the layer containing the coating material 111 is not too thick and the internal resistance of the battery can be made sufficiently small. As a result, the energy density of the battery can be increased.
  • the thickness of the layer containing the coating material 111 may be 1 nm or more and 40 nm or less.
  • the thickness of the layer containing the coating material 111 may be 1 nm or more and 40 nm or less.
  • the layer containing the coating material 111 has a thickness of 1 nm or more, direct contact between the positive electrode active material 110 and the solid electrolyte can be more sufficiently suppressed, and side reactions of the solid electrolyte can be suppressed. As a result, the charging and discharging efficiency of the battery is improved.
  • the layer containing the coating material 111 has a thickness of 40 nm or less, the internal resistance of the battery can be made more sufficiently small. As a result, the energy density of the battery can be increased.
  • the method for measuring the thickness of the layer containing the coating material 111 is not particularly limited.
  • the thickness can be estimated by observing a specific peak caused by the coating material 111 while etching the surface of the coating active material 130 by ion beam etching.
  • the thickness of the layer containing the coating material 111 may be measured by direct observation using a transmission electron microscope.
  • the coating material 111 may cover the entire surface of the particulate positive electrode active material 110. According to such a configuration, direct contact between the positive electrode active material 110 and solid electrolyte particles is suppressed, and side reactions of the solid electrolyte can be suppressed. Therefore, charging and discharging efficiency can be improved.
  • the coating material 111 may cover only a part of the surface of the particulate positive electrode active material 110.
  • the particles of the plurality of positive electrode active materials 110 come into direct contact with each other through the portions not having the coating material 111, thereby improving the electron conductivity between the particles of the positive electrode active materials 110. This allows the battery to operate at high output.
  • the positive electrode active material 110 includes a material that has the property of intercalating and deintercalating metal ions (for example, lithium ions).
  • a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion material, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxysulfide, a transition metal oxynitride, etc. can be used.
  • manufacturing costs can be reduced and the average discharge voltage can be increased.
  • the positive electrode active material 110 may include a lithium-containing transition metal oxide having a layered rock salt structure.
  • a lithium-containing transition metal oxide having a layered rock-salt structure allows easy insertion and removal of lithium, and has a large capacity per unit weight. Therefore, by using such a material, excellent charge/discharge characteristics can be achieved.
  • lithium-containing transition metal oxides having a layered rock salt structure examples include nickel-cobalt-lithium aluminate, nickel-cobalt-lithium manganate, and lithium cobalt oxide.
  • the positive electrode active material 110 may include a single active material, or may include a plurality of active materials having mutually different compositions.
  • the positive electrode active material 110 may contain at least one selected from the group consisting of nickel-cobalt-lithium aluminate and nickel-cobalt-lithium manganate.
  • the positive electrode active material 110 may be nickel-cobalt-lithium aluminate or nickel-cobalt-lithium manganate.
  • the positive electrode active material 110 may be, for example, Li(NiCoAl)O 2 .
  • the positive electrode active material 110 may be, for example, Li(NiCoMn)O 2 . According to such a configuration, the energy density and charging/discharging efficiency of the battery can be further increased.
  • the electronic conductivity of the positive electrode active material 110 is 10 -9 Scm -1 or more, 10 -8 Scm -1 or more, 10 -7 Scm -1 or more, 10 -6 Scm -1 or more, 10 at room temperature (25°C). -5 Scm -1 or more, or 10 -4 Scm -1 or more may be used.
  • the positive electrode active material 110 has high electronic conductivity, the oxidation reaction of the solid electrolyte at the positive electrode of the battery is likely to be promoted. In such cases, the technology of the present disclosure is more effective.
  • the positive electrode active material 110 has, for example, a particle shape.
  • the shape of the particles of the positive electrode active material 110 is not particularly limited.
  • the shape of the particles of the positive electrode active material 110 may be spherical, ellipsoidal, scaly, or fibrous.
  • the coated active material 130 can be manufactured, for example, by the method described below.
  • the positive electrode active material 110 is prepared. Powder of the positive electrode active material 110 is commercially available.
  • the positive electrode active material 110 is coated with a coating material.
  • the coating method is not particularly limited. Examples of methods for coating the positive electrode active material 110 with the coating material include a liquid phase coating method and a vapor phase coating method.
  • a precursor solution of a coating material is applied to the surface of the positive electrode active material 110.
  • the precursor solution can be a complex solution containing a peroxo complex of niobium ([Nb( O2 ) 4 ] 3- ) and lithium ions.
  • the complex solution can be obtained, for example, by preparing a transparent solution using hydrogen peroxide, niobic acid, and aqueous ammonia, and then adding a lithium compound to the transparent solution.
  • the lithium compound include LiOH, LiNO 3 , Li 2 SO 4 and the like.
  • the method of applying the precursor solution to the surface of the positive electrode active material 110 is not particularly limited.
  • the precursor solution can be applied to the surface of the positive electrode active material 110 using a tumbling flow granulation coating device.
  • the precursor solution can be applied to the surface of the positive electrode active material 110 by spraying the precursor solution onto the positive electrode active material 110 while rolling and fluidizing the positive electrode active material 110. .
  • a precursor film is formed on the surface of the positive electrode active material 110.
  • the precursor film is dried. Formation of the precursor film and drying of the precursor film may be performed in parallel.
  • a positive electrode active material 110 covered with lithium niobate is obtained.
  • the drying conditions are, for example, under a dry air atmosphere, at an ambient temperature of 200° C. to 300° C., and for 10 minutes or more and 720 minutes or less.
  • the covering material 111 can also be formed by a so-called sol-gel method. That is, the precursor solution may be a mixed solution (sol solution) of a solvent, lithium alkoxide, and niobium alkoxide. Lithium alkoxide includes lithium ethoxide. Examples of niobium alkoxide include niobium ethoxide.
  • the solvent is, for example, an alcohol such as ethanol. The amounts of lithium alkoxide and niobium alkoxide are adjusted depending on the target composition of the coating material. Water may be added to the precursor solution if necessary.
  • the precursor solution may be acidic or alkaline.
  • vapor phase coating methods include pulsed laser deposition (PLD), vacuum evaporation, sputtering, chemical vapor deposition (CVD), and plasma chemical vapor deposition.
  • PLD pulsed laser deposition
  • CVD chemical vapor deposition
  • plasma chemical vapor deposition plasma chemical vapor deposition.
  • an ion conductive material as a target is irradiated with a high-energy pulsed laser (for example, KrF excimer laser, wavelength: 248 nm), and the sublimated ion conductive material is deposited on the surface of the positive electrode active material 110.
  • a high-energy pulsed laser for example, KrF excimer laser, wavelength: 248 nm
  • highly densely sintered LiNbO 3 is used as a target.
  • the positive electrode active material 110 coated with the coating material is carbonated. Specifically, the positive electrode active material 110 coated with the coating material is brought into contact (exposed) to a processing gas containing carbon dioxide gas at a higher concentration than the atmosphere. According to such a method, the concentration of carbon constituting carbonate ions in the surface layer of the positive electrode active material 110 coated with the coating material can be increased.
  • the time for carbonation treatment is, for example, 10 minutes or more and 720 minutes or less.
  • the carbonic acid treatment may be performed at room temperature (20°C ⁇ 15°C) or at a temperature higher than room temperature. That is, in the carbonation treatment, the positive electrode active material 110 coated with the coating material may be heated while being brought into contact with the treatment gas. By heating, the concentration of carbon constituting carbonate ions in the surface layer of the positive electrode active material 110 coated with the coating material can be efficiently increased.
  • the ambient temperature during heating is, for example, 50°C or more and 300°C or less, preferably 100°C or more and 300°C or less. By appropriately adjusting the heating temperature, the concentration of carbon constituting carbonate ions can be appropriately controlled.
  • a treatment gas whose main component is carbon dioxide gas can be used.
  • the concentration of carbonate ions in the surface layer portion of the positive electrode active material 110 coated with the coating material can be efficiently increased.
  • pure carbon dioxide gas can be used as the process gas.
  • "Main component" means the component that is contained the most in volume ratio.
  • the coated active material 130 is obtained.
  • FIG. 2 is a cross-sectional view showing a schematic configuration of positive electrode material 1000 in Embodiment 2.
  • Positive electrode material 1000 is a mixture of coated active material 130 and solid electrolyte 100 in the first embodiment.
  • the positive electrode material 1000 includes a coated active material 130 and a solid electrolyte 100. Covered active material 130 and solid electrolyte 100 are in contact with each other.
  • the solid electrolyte 100 may include at least one selected from the group consisting of a sulfide solid electrolyte, a halide solid electrolyte, and an oxyhalide solid electrolyte. According to such a configuration, the ionic conductivity of the solid electrolyte 100 can be improved. Thereby, the resistance of the battery can be reduced.
  • halide solid electrolyte examples include Li 3 YX 6 , Li 2 MgX 4 , Li 2 FeX 4 , Li (Al, Ga, In) X 4 and Li 3 (Al, Ga, In) X 6 .
  • Examples of the oxyhalide solid electrolyte include Li a (Ta, Nb) b O c X d . a, b, c and d each independently have a value greater than 0. X includes at least one selected from the group consisting of F, Cl, Br, and I.
  • Sulfide solid electrolytes include Li 2 SP 2 S 5 , Li 2 S-SiS 2 , Li 2 SB 2 S 3 , Li 2 S-GeS 2 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 10 Examples include GeP 2 S 12 .
  • LiX, Li2O , MOq , LipMOq , etc. may be added to these.
  • the element X in “LiX” is at least one selected from the group consisting of F, Cl, Br, and I.
  • the element M in “MO q " and " Lip MO q " is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn.
  • p and q in "MO q " and " Lip MO q " are each independent natural numbers.
  • the solid electrolyte 100 may include two or more selected from the above materials.
  • Solid electrolyte 100 may include, for example, a halide solid electrolyte and a sulfide solid electrolyte.
  • the shape of the solid electrolyte 100 is not particularly limited, and may be, for example, acicular, spherical, or ellipsoidal.
  • the solid electrolyte 100 may have a particulate shape.
  • the median diameter when the solid electrolyte 100 has a particulate shape (for example, spherical shape), the median diameter may be 100 ⁇ m or less.
  • the coated active material 130 and the solid electrolyte 100 can form a good dispersion state in the positive electrode material 1000. This improves the charging and discharging characteristics of the battery.
  • the median diameter of solid electrolyte 100 may be 10 ⁇ m or less.
  • the coated active material 130 and the solid electrolyte 100 can form a good dispersion state.
  • the median diameter of the solid electrolyte 100 may be smaller than the median diameter of the coated active material 130.
  • the solid electrolyte 100 and the coated active material 130 can form a better dispersion state in the positive electrode material 1000.
  • the median diameter of the coated active material 130 may be 0.1 ⁇ m or more and 100 ⁇ m or less.
  • the coated active material 130 and the solid electrolyte 100 can form a good dispersion state in the positive electrode material 1000. As a result, the charging and discharging characteristics of the battery are improved.
  • the median diameter of the coated active material 130 is 100 ⁇ m or less, a sufficient diffusion rate of lithium within the coated active material 130 is ensured. This allows the battery to operate at high output.
  • the median diameter of the coated active material 130 may be larger than the median diameter of the solid electrolyte 100. Thereby, the coated active material 130 and the solid electrolyte 100 can form a good dispersion state.
  • the particles of the solid electrolyte 100 and the particles of the coated active material 130 may be in contact with each other, as shown in FIG. 2.
  • the solid electrolyte 100 may fill spaces between particles of the coated active material 130.
  • coating material 111 and solid electrolyte 100 come into contact with each other.
  • the positive electrode material 1000 may include a plurality of solid electrolyte 100 particles and a plurality of coated active material 130 particles.
  • the content of solid electrolyte 100 and the content of coated active material 130 in positive electrode material 1000 may be the same or different.
  • volume diameter means the particle diameter 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 measurement device or an image analysis device.
  • Embodiment 3 (Embodiment 3) Embodiment 3 will be described below. Descriptions that overlap with those of the first embodiment described above will be omitted as appropriate.
  • FIG. 3 is a cross-sectional view showing a schematic configuration of a battery 2000 in Embodiment 3.
  • the battery 2000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203.
  • the positive electrode 201 includes the positive electrode material 1000 in Embodiment 1.
  • the benefits described in Embodiment 1 can be obtained in positive electrode 201.
  • the electrolyte layer 202 is arranged between the positive electrode 201 and the negative electrode 203.
  • the charging and discharging efficiency of the battery 2000 can be improved.
  • the thickness of the positive electrode 201 may be 10 ⁇ m or more and 500 ⁇ m or less. When the thickness of the positive electrode 201 is 10 ⁇ m or more, a sufficient energy density of the battery 2000 is ensured. When the thickness of the positive electrode 201 is 500 ⁇ m or less, operation at high output is possible.
  • the electrolyte layer 202 is a layer containing an electrolyte.
  • the electrolyte is, for example, a solid electrolyte. That is, the electrolyte layer 202 may be a solid electrolyte layer.
  • the solid electrolyte 100 contained in the positive electrode material 1000 may be referred to as a "first solid electrolyte”
  • the solid electrolyte contained in the electrolyte layer 202 may be referred to as a "second solid electrolyte”.
  • the materials exemplified in Embodiment 2 may be used. That is, the electrolyte layer 202 may include a solid electrolyte having the same composition as the solid electrolyte 100 contained in the positive electrode material 1000. Electrolyte layer 202 may include, for example, a sulfide solid electrolyte.
  • the charging and discharging efficiency of the battery 2000 can be further improved.
  • the electrolyte layer 202 may include a solid electrolyte having a composition different from that of the solid electrolyte 100 contained in the positive electrode material 1000.
  • electrolyte layer 202 may include a sulfide solid electrolyte having a composition different from that of solid electrolyte 100.
  • the output density and charge/discharge efficiency of the battery 2000 can be improved.
  • the electrolyte layer 202 may include at least one selected from the group consisting of a halide solid electrolyte, an oxyhalide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte.
  • a halide solid electrolyte As the halide solid electrolyte and the oxyhalide solid electrolyte, the materials exemplified in Embodiment 2 can be used.
  • oxide solid electrolytes examples include NASICON type solid electrolytes represented by LiTi 2 (PO 4 ) 3 and its element substituted products, (LaLi)TiO 3 -based perovskite type solid electrolytes, Li 14 ZnGe 4 O 16 , Li LISICON-type solid electrolytes represented by 4 SiO 4 , LiGeO 4 and their element-substituted products; garnet-type solid electrolytes represented by Li 7 La 3 Zr 2 O 12 and its element-substituted products; Li 3 N and its H-substituted products.
  • NASICON type solid electrolytes represented by LiTi 2 (PO 4 ) 3 and its element substituted products
  • (LaLi)TiO 3 -based perovskite type solid electrolytes Li 14 ZnGe 4 O 16
  • Li LISICON-type solid electrolytes represented by 4 SiO 4 , LiGeO 4 and their element-substituted products
  • garnet-type solid electrolytes
  • Li 3 PO 4 and its N-substituted product glass or glass in which materials such as Li 2 SO 4 and Li 2 CO 3 are added to a base material containing Li - BO compounds such as LiBO 2 and Li 3 BO 3 Ceramics etc. can be used.
  • 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 can contain a large amount of lithium salt, so that the ionic conductivity can be further increased.
  • Lithium salts 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 )( SO2C4F9 ) , LiC( SO2CF3 ) 3 , etc. may be used.
  • the lithium salt 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 complex hydride solid electrolyte for example, LiBH 4 --LiI, LiBH 4 --P 2 S 5 , etc. can be used.
  • the electrolyte layer 202 may contain the second solid electrolyte as a main component. That is, the electrolyte layer 202 may contain the second solid electrolyte in a mass proportion of 50% or more (that is, 50% or more by mass) relative to the total mass of the electrolyte layer 202 .
  • the charging and discharging characteristics of the battery 2000 can be further improved.
  • the electrolyte layer 202 may contain the second solid electrolyte in a mass proportion of 70% or more (i.e., 70% by mass or more) with respect to the total mass of the electrolyte layer 202.
  • the charging and discharging characteristics of the battery 2000 can be further improved.
  • the electrolyte layer 202 contains the second solid electrolyte as a main component, and further contains inevitable impurities, starting materials, by-products, decomposition products, etc. used when synthesizing the second solid electrolyte. You can stay there.
  • the electrolyte layer 202 may contain 100% (i.e., 100% by mass) of the second solid electrolyte in terms of mass proportion to the total mass of the electrolyte layer 202, excluding unavoidable impurities.
  • the charging and discharging characteristics of the battery 2000 can be further improved.
  • the electrolyte layer 202 may be composed only of the second solid electrolyte.
  • the electrolyte layer 202 may include only one type of solid electrolyte selected from the group of solid electrolytes described above, or may include two or more types of solid electrolytes selected from the group of solid electrolytes described above. .
  • the plurality of solid electrolytes have mutually different compositions.
  • electrolyte layer 202 may include a halide solid electrolyte and a sulfide solid electrolyte.
  • the thickness of the electrolyte layer 202 may be 1 ⁇ m or more and 300 ⁇ m or less. When the thickness of the electrolyte layer 202 is 1 ⁇ m or more, the positive electrode 201 and the negative electrode 203 can be separated more reliably. When the thickness of the electrolyte layer 202 is 300 ⁇ m or less, high output operation can be achieved.
  • the negative electrode 203 includes a material that has the property of intercalating and deintercalating metal ions (for example, lithium ions). Negative electrode 203 includes, for example, a negative electrode active material.
  • 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.
  • metal materials include lithium metal and lithium alloys.
  • Examples of carbon materials include natural graphite, coke, under-graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. From the viewpoint of capacity density, silicon (Si), tin (Sn), a silicon compound, or a tin compound can be used.
  • the negative electrode 203 may include a solid electrolyte (third solid electrolyte). According to such a configuration, the lithium ion conductivity inside the negative electrode 203 is increased and operation at high output is possible.
  • the materials mentioned above may be used as the solid electrolyte.
  • 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 median diameter of the particles of the negative electrode active material is 0.1 ⁇ m or more, the particles of the negative electrode active material and the solid electrolyte can form a good dispersion state in the negative electrode 203. This improves the charging and discharging characteristics of the battery 2000.
  • the median diameter of the particles of the negative electrode active material is 100 ⁇ m or less, lithium diffusion within the particles of the negative electrode active material becomes faster. Therefore, battery 2000 can operate at high output.
  • the median diameter of the particles of the negative electrode active material may be larger than the median diameter of the particles of the solid electrolyte included in the negative electrode 203. This makes it possible to form a good dispersion state between the negative electrode active material and the solid electrolyte.
  • the volume ratio of the negative electrode active material to the solid electrolyte in the negative electrode 203 is expressed as "v2:100-v2"
  • the volume ratio v2 of the negative electrode active material may satisfy 30 ⁇ v2 ⁇ 95.
  • 30 ⁇ v2 is satisfied, a sufficient energy density of the battery 2000 is ensured.
  • v2 ⁇ 95 is satisfied, operation at high output is possible.
  • the thickness of the negative electrode 203 may be 10 ⁇ m or more and 500 ⁇ m or less. When the thickness of the negative electrode 203 is 10 ⁇ m or more, a sufficient energy density of the battery 2000 is ensured. When the thickness of the negative electrode 203 is 500 ⁇ m or less, operation at high output is possible.
  • At least one of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a binder for the purpose of improving adhesion between particles.
  • the binder is used to improve the binding properties of the materials constituting the electrode.
  • a binder polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polyacrylic acid methyl ester, polyacrylic acid ethyl ester, polyacrylic acid, etc.
  • Acrylic acid hexyl ester polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene butadiene rubber, Examples include carboxymethylcellulose.
  • a copolymer of two or more selected materials may be used. Moreover, two or more selected from these may be mixed and used as a binder.
  • At least one of the positive electrode 201 and the negative electrode 203 may contain a conductive aid for the purpose of increasing electronic conductivity.
  • conductive aids include graphites such as natural graphite or artificial graphite, carbon blacks such as acetylene black and Ketjen black, conductive fibers such as carbon fibers or metal fibers, carbon fluoride, and metal powders such as aluminum.
  • conductive whiskers such as zinc oxide or potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene.
  • the battery 2000 in Embodiment 3 can be configured as a battery in various shapes, such as a coin shape, a cylindrical shape, a square shape, a sheet shape, a button shape, a flat shape, and a stacked type.
  • Example 1 [Preparation of coated active material] (Preparation of complex solution) 870 g of hydrogen peroxide solution with a concentration of 30% by mass was placed in a container, and 987 g of ion-exchanged water and 177 g of niobic acid (Nb 2 O 5 .3H 2 O (Nb 2 O 5 water content 72%)) were added. Next, 87.9 g of ammonia water having a concentration of 28% by mass was added to the container. Next, the contents in the container were sufficiently stirred to obtain a clear solution.
  • LiOH.H 2 O lithium hydroxide monohydrate
  • a complex solution containing a lithium niobate precursor is sprayed onto the positive electrode active material using a tumbling fluid coating device (manufactured by Powrex, MP-01), and the complex solution is dried in parallel with the spraying. A layer was formed on the surface of the particles of positive electrode active material.
  • the amount of complex solution used was 720 g. LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA, average particle size 5 ⁇ m) was used as a positive electrode active material.
  • the amount of positive electrode active material used was 2000 g.
  • the operating conditions of the tumbling fluid coating apparatus were as follows.
  • Intake gas Nitrogen Intake temperature: 200°C Intake air volume: 0.4m 3 /min Rotor rotation speed: 400 revolutions per minute Spraying speed: 10g/min
  • Heat treatment A muffle furnace was used to heat-treat the positive electrode active material coated with a lithium niobate precursor.
  • the heat treatment conditions were 220° C. for 4 hours.
  • a coated active material having a positive electrode active material and lithium niobate attached to the surface thereof was obtained. That is, the coating material in Example 1 was lithium niobate (LiNbO 3 ).
  • Carbonation treatment After the coated active material was placed in a tubular electric furnace, carbon dioxide gas (CO 2 gas) was passed through the furnace at a flow rate of 1 L/min and left standing for 1 hour to bring the coated active material into contact with the carbon dioxide gas. As a result, a powdery coated active material of Example 1 was obtained. The purity of carbon dioxide gas was 99.999%.
  • XPS measurement of coated active material XPS measurement of the coated active material of Example 1 was conducted under the following conditions. QuanteraSXM (manufactured by ULVAC-PHI) was used for the XPS measurement.
  • X-ray source Al monochrome (25W, 15kV)
  • Electron/ion neutralization gun ON Photoelectron extraction angle: 45 degrees
  • the ratio X C was determined.
  • peak fitting was performed using a pseudo-Voigt function. Since the peak position of each bond cannot be uniformly determined due to the influence of charging, fitting was performed by fixing the relative positions and intensity ratios of the multiple peaks of each component.
  • Niobium (Nb) was selected as the element to be measured, and the scanning range of binding energy was set from 200 eV to 212 eV (Nb3d orbit).
  • the Nb atomic ratio X Nb was calculated using the Nb3d peak.
  • VGCF vapor grown carbon fiber
  • SEBS styrene-ethylene-butylene-styrene block copolymer
  • SEBS styrene-ethylene-butylene-styrene block copolymer
  • the obtained mixture was sufficiently dispersed using an ultrasonic homogenizer to prepare a negative electrode paste.
  • the amount of the conductive aid was 1 part by mass based on 100 parts by mass of the negative electrode active material.
  • the amount of binder was 2 parts
  • a positive electrode paste was applied to an aluminum foil as a positive electrode current collector by a blade method using an applicator to form a coating film.
  • the coated film was dried on a hot plate at 100°C for 30 minutes. Thereby, a positive electrode having a positive electrode current collector and a positive electrode active material layer was obtained.
  • the positive electrode was pressed.
  • An electrolyte layer forming paste containing a sulfide solid electrolyte was applied to the surface of the pressed positive electrode active material layer using a die coater to obtain a laminate of the positive electrode and the coating film.
  • the laminate was dried on a 100°C hot plate for 30 minutes. Thereafter, the laminate was roll pressed at a linear pressure of 2 ton/cm. Thereby, a positive electrode side laminate having a positive electrode current collector, a positive electrode active material layer, and a solid electrolyte layer was obtained.
  • a negative electrode paste was applied to a nickel foil serving as a negative electrode current collector to form a coating film.
  • the coated film was dried on a hot plate at 100°C for 30 minutes. Thereby, a negative electrode having a negative electrode current collector and a negative electrode active material layer was obtained.
  • the negative electrode was pressed.
  • An electrolyte layer forming paste was applied to the surface of the pressed negative electrode active material layer using a die coater to obtain a laminate of the negative electrode and the coating film.
  • the laminate was dried on a 100°C hot plate for 30 minutes. Thereafter, the laminate was roll pressed at a linear pressure of 2 ton/cm. Thereby, a negative electrode side laminate having a negative electrode current collector, a negative electrode active material layer, and a solid electrolyte layer was obtained.
  • the positive electrode side laminate and the negative electrode side laminate were each punched out into a predetermined shape.
  • the positive electrode side laminate and the negative electrode side laminate were stacked so that the solid electrolyte layers were in contact with each other. Thereafter, the positive electrode side laminate and the negative electrode side laminate were roll pressed under the conditions of 130° C. and a linear pressure of 2 ton/cm. Thereby, a power generation element having a positive electrode, a solid electrolyte layer, and a negative electrode in this order was obtained.
  • a positive electrode terminal and a negative electrode terminal were attached to the obtained power generation element, and it was sealed in a container made of a laminate film and restrained under a pressure of 5 MPa to obtain an all-solid-state battery of Example 1.
  • the direct current resistance of the all-solid-state battery was measured by the following method. Constant current charging was performed with a current of 1C, and after the cell voltage reached 2.95V, constant voltage charging was performed with 2.95V, and charging was terminated when the charging current reached 0.01C. Next, constant current discharge was performed with a current of 1 C, and the discharge was terminated when the cell voltage decreased to 1.5 V.
  • the all-solid-state battery was charged again to 2.2V with a current of C/3, and then discharged with a current of 4C.
  • the DC resistance was calculated by dividing the difference between the open circuit voltage immediately before discharging at 4C and the voltage 10 seconds after the start of discharge by the 4C current value.
  • the calculated DC resistance was regarded as the "initial resistance" before the durability test. The results are shown in Table 1 and FIG. 4.
  • FIG. 4 is a graph showing the relationship between X C /(X Nb +X C ) and initial resistance, and the relationship between X C /(X Nb + X C ) and resistance change rate.
  • the horizontal axis represents the value of X C /(X Nb +X C ).
  • the vertical axis represents the initial resistance of Comparative Example 1 and the ratio to the resistance change rate.
  • Example 2 ⁇ A coated active material of Example 2 was produced in the same manner as in Example 1, except that the carbonic acid treatment was performed under the following conditions.
  • Examples 3 to 6>> A coated active material was produced in the same manner as in Example 2, except that the carbonic acid treatment was performed under the following conditions.
  • the C1sXPS spectrum of the coated active material of Example 6 is shown in FIG.
  • Example 1 A coated active material of Comparative Example 1 was produced in the same manner as in Example 1, except that the carbonation treatment was omitted.
  • the C1sXPS spectrum of the coated active material of Comparative Example 1 is shown in FIG.
  • Lithium compounds such as Li 2 O absorb moisture and/or carbon dioxide in the air, producing compounds such as LiOH and LiHCO 3 . These compounds are electrochemically unstable and active. On the other hand, by carbonation treatment, these compounds are converted into Li 2 CO 3 and stabilized. As a result, it is thought that side reactions inside the battery were suppressed and the initial resistance of the battery was reduced.
  • FIG. 5 is a graph showing the elemental profile in the depth direction of the coated active material of Comparative Example 1.
  • the detected elements are carbon and niobium.
  • the horizontal axis represents the depth from the surface.
  • the vertical axis represents the atomic ratio of carbon and niobium to all elements.
  • the concentration of niobium was approximately constant from the surface to 30 nm. In the region deeper than 30 nm, the concentration of niobium gradually decreased. It is thought that LiNbO 3 exists up to about 30 nm from the surface, and etching deeper than 30 nm causes defects in the layer of the coating material, which reduces the signal.
  • FIG. 6 is a graph showing the elemental profile in the depth direction of the coated active material of Example 4. Near the surface, the concentration of niobium was low and the concentration of carbon was high. That is, a layer containing carbon constituting carbonate ions was formed on the surface of the coated active material. The carbon ratio decreased rapidly from the surface to a depth of around 20 nm. After that, the proportion of carbon gradually decreased. Since the ratio of niobium reached the maximum at 20 nm, it is considered that the thickness of the carbonate layer was formed to be at least about 20 nm in terms of SiO 2 . The carbon ratio was constant after 50 nm. From this, it is considered that the maximum thickness of the carbonate layer is about 50 nm. It is thought that the thickness of the carbonic acid layer increases as the treatment temperature increases in the carbonic acid treatment, and increases as the treatment time increases in the carbonic acid treatment.
  • the battery of the present disclosure can be used, for example, as an all-solid-state secondary battery.

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013175412A (ja) * 2012-02-27 2013-09-05 Sumitomo Electric Ind Ltd 非水電解質電池
JP2014238957A (ja) * 2013-06-07 2014-12-18 Ｄｏｗａホールディングス株式会社 正極活物質粉末およびその製造法
JP2020167042A (ja) * 2019-03-29 2020-10-08 住友化学株式会社 全固体リチウムイオン電池用正極活物質、電極および全固体リチウムイオン電池
WO2022044720A1 (ja) * 2020-08-24 2022-03-03 住友化学株式会社 リチウム二次電池用正極活物質、リチウム二次電池用正極及びリチウム二次電池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013175412A (ja) * 2012-02-27 2013-09-05 Sumitomo Electric Ind Ltd 非水電解質電池
JP2014238957A (ja) * 2013-06-07 2014-12-18 Ｄｏｗａホールディングス株式会社 正極活物質粉末およびその製造法
JP2020167042A (ja) * 2019-03-29 2020-10-08 住友化学株式会社 全固体リチウムイオン電池用正極活物質、電極および全固体リチウムイオン電池
WO2022044720A1 (ja) * 2020-08-24 2022-03-03 住友化学株式会社 リチウム二次電池用正極活物質、リチウム二次電池用正極及びリチウム二次電池

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