WO2023090048A1 - 負極活物質およびその負極活物質を含む固体電池 - Google Patents

負極活物質およびその負極活物質を含む固体電池 Download PDF

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WO2023090048A1
WO2023090048A1 PCT/JP2022/039245 JP2022039245W WO2023090048A1 WO 2023090048 A1 WO2023090048 A1 WO 2023090048A1 JP 2022039245 W JP2022039245 W JP 2022039245W WO 2023090048 A1 WO2023090048 A1 WO 2023090048A1
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negative electrode
active material
electrode active
solid electrolyte
solid
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French (fr)
Japanese (ja)
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良平 高野
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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Priority to JP2023561478A priority Critical patent/JP7711766B2/ja
Priority to CN202280076526.0A priority patent/CN118266101A/zh
Publication of WO2023090048A1 publication Critical patent/WO2023090048A1/ja
Priority to US18/649,003 priority patent/US20240290964A1/en
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • C01G31/006—Compounds containing vanadium, with or without oxygen or hydrogen, and containing two or more other elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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
    • H01M2004/027—Negative 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
    • 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

  • the present invention relates to a negative electrode active material and a solid battery containing the negative electrode active material.
  • the battery with the above configuration has the risk of leakage of the electrolyte, and there is a problem that the organic solvent or the like used in the electrolyte is a combustible substance. Therefore, it has been proposed to use a solid electrolyte instead of the electrolytic solution.
  • a solid secondary battery so-called "solid battery” in which a solid electrolyte is used as an electrolyte and other components are also made of solid materials is being developed.
  • LVO unsubstituted ⁇ II -Li 3 VO 4
  • LVO ⁇ -Li 3 VO 4
  • the inventor of the present invention realized that there were problems to be overcome in the above-described conventional technology, and found the need to take measures to address them. Specifically, the inventors of the present invention have found the following new problems.
  • a solid battery using an unsubstituted ⁇ II —Li 3 VO 4 (LVO) type crystal structure as a negative electrode active material has a high initial reversible capacity.
  • the interfacial resistance between the negative electrode active material and the solid electrolyte was relatively high.
  • the solid-state battery using the ⁇ -Li 3 VO 4 (LVO) crystal structure as the negative electrode active material also had a high initial reversible capacity, but a relatively low capacity retention rate when the charging rate was increased.
  • the present invention has been made in view of such problems. That is, the present invention aims to provide a solid battery in which the capacity retention rate is sufficiently high when the charging rate is increased, and the interfacial resistance between the negative electrode active material and the solid electrolyte having a garnet-type crystal structure is sufficiently low. aim.
  • the present invention relates to a negative electrode active material having a ⁇ -LVO type crystal structure, wherein a part of the V element in the ⁇ -LVO type crystal structure is replaced with one or more elements capable of forming a four-coordinated structure.
  • the present invention also provides A solid battery comprising a negative electrode layer, a positive electrode layer, and a solid electrolyte layer disposed between the negative electrode layer and the positive electrode layer,
  • the negative electrode layer relates to a solid battery including the negative electrode active material.
  • a solid battery containing the negative electrode active material of the present invention has a sufficiently high capacity retention rate when the charging rate is increased, and the interfacial resistance between the negative electrode active material and the solid electrolyte having a garnet-type crystal structure is sufficiently low.
  • FIG. 1 is a schematic graph for explaining the evaluation method of interfacial resistance characteristics, showing the relationship between the real component (Za) and the imaginary component (Zb) of impedance.
  • FIG. 2 shows charge-discharge curves of the solid battery produced in Comparative Example 2.
  • Solid battery broadly refers to a battery in which the electrolyte layer, which is one of its components, is solid, and in a narrow sense, refers to a battery in which the components (particularly all components) are solid.
  • battery includes so-called “secondary batteries” that can be repeatedly charged and discharged, and “primary batteries” that can only be discharged.
  • a “solid battery” is preferably a "secondary battery”.
  • “Secondary battery” is not limited to its name, and can include, for example, "power storage device”.
  • the solid battery of the present invention includes a positive electrode layer, a negative electrode layer and a solid electrolyte layer, and usually has a laminated structure in which the positive electrode layer and the negative electrode layer are laminated with the solid electrolyte layer interposed therebetween.
  • Each of the positive electrode layer and the negative electrode layer may be laminated with two or more layers as long as the solid electrolyte layer is provided therebetween.
  • the solid electrolyte layer is in contact with and sandwiched between the positive electrode layer and the negative electrode layer.
  • the positive electrode layer and the solid electrolyte layer may be co-fired, and/or the negative electrode layer and the solid electrolyte layer may be co-fired.
  • Firing integrally means that two or more members (especially layers) that are adjacent or in contact with each other are fired together. Both of the two or more members (especially layers) may be sintered bodies, and are preferably sintered integrally.
  • the solid battery of the present invention is a "fired solid battery” or a “co-fired solid battery” in the sense that the positive electrode layer and the solid electrolyte layer are integrally fired and/or the negative electrode layer and the solid electrolyte layer are integrally fired. may be referred to as "solid-state batteries”.
  • the negative electrode layer contains a negative electrode active material and may further contain a solid electrolyte.
  • both the negative electrode active material and the solid electrolyte may have the form of a fired body.
  • the solid electrolyte bonds the negative electrode active material particles, and the negative electrode active material particles and the negative electrode active material particles and the solid electrolyte are bonded to each other by firing. It may have the form of a sintered body.
  • the negative electrode active material has a ⁇ -LVO type structure
  • part of the V element in the ⁇ -LVO type crystal structure is replaced with one or more elements capable of forming a four-coordinated structure. That the negative electrode active material has a ⁇ -LVO type structure means that the negative electrode active material (particularly its particles) has a ⁇ -LVO type crystal structure.
  • the negative electrode layer and the solid electrolyte layer contains a solid electrolyte having a garnet crystal structure
  • the negative electrode layer does not contain a negative electrode active material having a ⁇ -LVO type structure (for example, when the negative electrode layer has a ⁇ -
  • the capacity retention rate decreases when the charging rate is increased.
  • the capacity retention rate characteristic is a characteristic related to the capacity retention rate when the charging rate is increased, and is the charge capacity (C 0.1 ) when charging at 0.1 C when charging at 1 C It is a characteristic related to the maintenance rate ((C 1 /C 0.1 ) ⁇ 100 (%)) of the charge capacity (C 1 ) of the battery.
  • the higher the capacity retention rate characteristic the better.
  • the charge capacity at the same voltage is lower than when charging at a low rate.
  • the interfacial resistance characteristic is a characteristic related to the interfacial resistance between the negative electrode active material and the solid electrolyte, and the smaller the interfacial resistance characteristic, the better.
  • the ⁇ -LVO type crystal structure of the negative electrode active material include, for example, a ⁇ II -Li 3 VO 4 type crystal structure.
  • the negative electrode active material preferably has a ⁇ II —Li 3 VO 4 type structure from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics.
  • At least the main component contained in the negative electrode active material should have a ⁇ -LVO type crystal structure.
  • That the negative electrode active material has a ⁇ II —Li 3 VO 4 type structure means that the negative electrode active material (especially particles thereof) has a ⁇ II —Li 3 VO 4 type crystal structure. It means having a crystal structure that can be recognized as a ⁇ II —Li 3 VO 4 type crystal structure by those skilled in the field of solid-state batteries.
  • a negative electrode active material having a ⁇ II —Li 3 VO 4 type structure means that the negative electrode active material (especially particles thereof) has a so-called ⁇ II —Li 3 VO 4 type crystal structure in X-ray diffraction. exhibit one or more major peaks at a given angle of incidence that correspond to the Miller indices characteristic of .
  • ICDD Card No. 01-073-6058 As an example of the negative electrode active material having the ⁇ II -Li 3 VO 4 type structure.
  • the negative electrode active material contains one or more elements that can have a four-coordinated structure.
  • An element capable of forming a tetracoordinated structure is an element capable of substituting for the V element forming a tetracoordinated structure in the ⁇ -LVO type crystal structure. Therefore, in the present invention, the negative electrode active material has a ⁇ -LVO type crystal structure, and at least one element in which a part of the V element in the ⁇ -LVO type crystal structure can have a four-coordination structure. has been replaced. When the negative electrode active material contains one or more elements capable of forming a four-coordinated structure, the capacity retention rate characteristics are improved.
  • the interfacial resistance between the solid electrolyte and the negative electrode active material is improved. Even if the negative electrode layer contains a negative electrode active material having a ⁇ -LVO type structure, if the negative electrode active material does not contain an element capable of forming a four-coordinated structure, the interfacial resistance characteristics between the solid electrolyte and the negative electrode active material decreases.
  • Elements that can have a four-coordinated structure include, for example, Zn, Al, Ga, Si, Ge, P, Ti, S, and Cr.
  • the negative electrode active material usually contains one or more elements selected from the group consisting of the above elements as elements capable of forming a four-coordinated structure. From the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics, the negative electrode active material may contain, as an element capable of forming a four-coordinated structure, one element selected from the group consisting of the above elements. preferable.
  • the negative electrode active material preferably contains one or more elements selected from the group consisting of Si, Ge, P and Ti as elements capable of forming a four-coordinated structure.
  • element preferably one type of element selected from the group, and more preferably one type of element selected from the group consisting of Si, Ge and Ti.
  • the amount of material of V element and the amount of material of Z can be calculated by calculating the below-described general formula (1) as the average chemical composition of the negative electrode active material.
  • r obtained from the amounts of V and Z contained in the negative electrode active material and y in the general formula (1) representing the average chemical composition of the negative electrode active material described in detail below correspond to each other. , and the value of r may be used as y in general formula (1).
  • the negative electrode active material has the general formula (1): It is preferable to have an average chemical composition represented by
  • A is Na (sodium), K (potassium), Mg (magnesium), Ca (calcium), Al (aluminum), Ga (gallium), Zn (zinc), Fe (iron), Cr (chromium) and Co (cobalt).
  • A is one or more elements selected from the group consisting of Mg, Al, Ga and Zn from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics.
  • Z is one or more elements capable of forming the four-coordinated structure described above.
  • Z is preferably one or more elements selected from the group consisting of Zn, Al, Ga, Si, Ge, P, Ti, S, and Cr, from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics.
  • Z is more preferably a single element selected from the above groups.
  • x satisfies the relationship 0 ⁇ x ⁇ 1.00.
  • x preferably satisfies the relationship 0 ⁇ x ⁇ 0.20, and is more preferably 0, from the viewpoint of further improving the capacity retention characteristics and interfacial resistance characteristics.
  • x is a number based on their total number.
  • y is a number based on the total number of y for each of those elements.
  • yZ1 the value corresponding to y for element Z1 that can have a 4-coordinated structure
  • yZ2 the value corresponding to y regarding the element Z2 that can have a 4-coordinated structure.
  • y Z1 and y Z2 amount of substance of Z2 / ⁇ amount of substance of V + (amount of substance of Z1 + amount of Z2
  • ⁇ should generally satisfy 0 ⁇ 0.5.
  • the amount of oxygen deficiency ⁇ may be considered to be 0 because it cannot be quantitatively analyzed using the latest equipment.
  • a is the average valence of A;
  • the average valence of A is (n1 ⁇ It is a value represented by a+n2 ⁇ b+n3 ⁇ c)/(n1+n2+n3).
  • b is the average valence of Z;
  • the average valence of Z is, for example, n1 elements X having a valence of a+, n2 elements Y having a valence b+, and n3 elements Z having a valence c+. is the same value as the average valence of
  • a particularly preferred value of y may be determined depending on Z.
  • y satisfies the following range, the ⁇ -LVO structure is easily obtained, which is preferable.
  • the composition is not necessarily limited to the following composition range, and the effect of the present invention can be obtained by including Z in the ⁇ -LVO structure.
  • Z contains Si (especially when Z is Si alone), y satisfies the relationship 0 ⁇ y ⁇ 0.050, and from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics, it is preferable is 0.005 ⁇ y ⁇ 0.050, more preferably 0.005 ⁇ y ⁇ 0.045, still more preferably 0.015 ⁇ y ⁇ 0.045, particularly preferably 0.025 ⁇ y ⁇ 0.045 fulfill the relationship. From the viewpoint of further improving the capacity retention rate characteristics and interfacial resistance characteristics, the above range of y in the case where Z contains Si can be y si , which is a value corresponding to y related to Si.
  • y when Z contains Ge (especially when Z is Ge alone), y satisfies the relationship 0 ⁇ y ⁇ 0.100, and from the viewpoint of further improving the capacity retention rate characteristics and interfacial resistance characteristics, Preferably 0.005 ⁇ y ⁇ 0.100, more preferably 0.015 ⁇ y ⁇ 0.100, still more preferably 0.030 ⁇ y ⁇ 0.100, particularly preferably 0.060 ⁇ y ⁇ 0.100 satisfy the relationship From the viewpoint of further improving the capacity retention characteristics and interfacial resistance characteristics, the above range of y when Z includes Ge can be y Ge , which is a value corresponding to y related to Ge.
  • y when Z contains Ti (especially when Z is Ti alone), y satisfies the relationship 0 ⁇ y ⁇ 0.150, and from the viewpoint of further improving the capacity retention rate characteristics and interfacial resistance characteristics, it is preferable is 0.005 ⁇ y ⁇ 0.130, more preferably 0.010 ⁇ y ⁇ 0.120, still more preferably 0.030 ⁇ y ⁇ 0.110, particularly preferably 0.060 ⁇ y ⁇ 0.110 fulfill the relationship. From the viewpoint of further improving the capacity retention rate characteristics and interfacial resistance characteristics, the above range of y in the case where Z includes Ti can be y Ti , which is a value corresponding to y related to Ti.
  • y satisfies the relationship 0 ⁇ y ⁇ 0.080, and from the viewpoint of further improving the capacity retention rate characteristics and interfacial resistance characteristics Therefore, preferably 0.010 ⁇ y ⁇ 0.060, more preferably 0.020 ⁇ y ⁇ 0.050, still more preferably 0.030 ⁇ y ⁇ 0.050, particularly preferably 0.035 ⁇ y ⁇ 0 satisfies the relationship of .045.
  • the above y corresponds to y for P (that is, y based only on P) and y for elements Z3 other than P.
  • y is a number based on the total number of Z3 .
  • y p satisfies the relationship of 0 ⁇ y p ⁇ 0.100, and from the viewpoint of further improving the capacity retention characteristics and interfacial resistance characteristics, preferably 0.005 ⁇ y p ⁇ 0.070, more preferably 0.070. 005 ⁇ y p ⁇ 0.050, more preferably 0.010 ⁇ y p ⁇ 0.040.
  • y Z3 satisfies the relationship of 0 ⁇ y Z3 ⁇ 0.100, and from the viewpoint of further improving the capacity retention characteristics and interfacial resistance characteristics, preferably 0.005 ⁇ y Z3 ⁇ 0.070, more preferably 0.005 ⁇ y Z3 ⁇ 0.050, more preferably 0.010 ⁇ y Z3 ⁇ 0.040.
  • y Z3 calculated as y Z3 amount of substance of element Z3 other than P/ ⁇ amount of substance of V + (amount of substance of P + amount of substance of element Z3 other than P) ⁇ should be filled.
  • the negative electrode active material examples include Li 3.01 (V 0.99 Si 0.01 )O 4 , Li 3.02 (V 0.98 Si 0.02 )O 4 , Li 3.04 (V 0.96Si0.04 ) O4 , Li3.01 ( V0.98Ge0.02 ) O4 , Li3.02 ( V0.95Ge0.05 ) O4 , Li3.04 ( V0.91Ge0.09 ) O4 , Li3.01 ( V0.98Ti0.02 ) O4 , Li3.02 ( V0.96Ti0.04 ) O4 , Li3.10 (V 0.90 Ti 0.10 )O 4 , Li 3.02 (V 0.96 Si 0.02 P 0.02 )O 4 ) and the like.
  • the chemical composition of the negative electrode active material may be an average chemical composition.
  • the average chemical composition of the negative electrode active material means the average value of the chemical composition of the negative electrode active material in the thickness direction of the negative electrode layer.
  • the average chemical composition of the negative electrode active material is determined by breaking the solid battery and using SEM-EDX (energy dispersive X-ray spectroscopy) or WDX (wavelength dispersive X-ray spectroscopy). Analysis and measurement can be performed by performing composition analysis by EDX or WDX in a field of view that fits. In the above composition analysis, the average chemical composition of the negative electrode active material and the average chemical composition of the solid electrolyte described later in the negative electrode layer can be automatically distinguished and measured according to their compositions.
  • the negative electrode active material can be produced, for example, by the following method. First, a raw material compound containing a predetermined metal atom is weighed so as to have a predetermined chemical composition, and water is added and mixed to obtain a slurry. The slurry is dried, calcined at 700° C. or more and 1000° C. or less for 4 hours or more and 6 hours or less, and pulverized to obtain a negative electrode active material.
  • the average particle diameter of the negative electrode active material is not particularly limited. For example, it may be 0.01 ⁇ m or more and 20 ⁇ m or less, preferably 0.1 ⁇ m or more and 5 ⁇ m or less.
  • the average particle size of the negative electrode active material for example, 10 to 100 particles are randomly selected from the SEM image, and the average particle size (arithmetic average) can be obtained by simply averaging the particle sizes. can.
  • the particle size is the diameter of a spherical particle assuming that the particle is a perfect sphere.
  • Such a particle size can be obtained, for example, by cutting out a cross-section of a solid-state battery, taking a cross-sectional SEM image using an SEM, and then using image analysis software (e.g., "Azo-kun" (manufactured by Asahi Kasei Engineering Co., Ltd.)).
  • image analysis software e.g., "Azo-kun" (manufactured by Asahi Kasei Engineering Co., Ltd.)
  • the particle diameter R can be determined by the following formula.
  • the average particle size of the negative electrode active material in the negative electrode layer can be automatically measured by specifying the negative electrode active material according to the composition during the measurement of the average chemical composition described above.
  • the particle size of the negative electrode active material can be easily determined by subjecting it to thermal etching after polishing. Therefore, thermal etching may be performed before measuring the average particle size.
  • the average particle size of the negative electrode active material may be the average particle size after heat treatment at 700° C. for 1 hour after polishing.
  • the volume ratio of the negative electrode active material in the negative electrode layer is not particularly limited, and from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics, it is preferably 20% or more and 80% or less, and 30% or more and 75% or less. more preferably 30% or more and 60% or less.
  • the volume ratio of the negative electrode active material in the negative electrode layer can be measured from the SEM image after processing the FIB cross section. Specifically, a cross section of the negative electrode layer is observed using SEM-EDX and/or WDX. By judging that the site where V is detected from EDX and/or WDX is the negative electrode active material and calculating the area ratio of the site, the volume ratio of the negative electrode active material can be measured.
  • the particle shape of the negative electrode active material in the negative electrode layer is not particularly limited, and may be spherical, flat, or irregular, for example.
  • the negative electrode layer may further contain a solid electrolyte in addition to the negative electrode active material.
  • the solid electrolyte contained in the negative electrode layer is not particularly limited. glass-ceramic lithium-ion conductors (for example, phosphate compounds containing lithium, aluminum and titanium as constituent elements (LATP), and phosphate compounds containing lithium, aluminum and germanium as constituent elements (LAGP)), and the like.
  • At least one of the negative electrode layer and the later-described solid electrolyte layer (especially at least the negative electrode layer, preferably both the negative electrode layer and the solid electrolyte layer) preferably contains a solid electrolyte having a garnet-type crystal structure.
  • At least one of the negative electrode layer and the solid electrolyte layer contains a solid electrolyte having a garnet-type crystal structure, so that excellent capacity retention characteristics can be obtained. Rather, it is because excellent interfacial resistance characteristics between the negative electrode active material and the solid electrolyte having the garnet-type crystal structure can be obtained.
  • At least one of the negative electrode layer and the solid electrolyte layer includes a solid electrolyte having a garnet-type crystal structure means that one of the negative electrode layer and the solid electrolyte layer may include a solid electrolyte having a garnet-type crystal structure, or both of them.
  • both the negative electrode layer and the solid electrolyte layer may contain a solid electrolyte having a garnet-type crystal structure.
  • the solid electrolyte having a garnet-type crystal structure contained in the negative electrode layer and the solid electrolyte having a garnet-type crystal structure contained in the solid electrolyte layer may have the same chemical composition, or may have different chemical compositions from each other. From the viewpoint of further improving capacity retention rate characteristics and interfacial resistance characteristics, both the negative electrode layer and the solid electrolyte layer preferably contain a solid electrolyte having a garnet-type crystal structure.
  • a solid electrolyte having a garnet-type crystal structure means not only a solid electrolyte having a "garnet-type crystal structure” but also a solid electrolyte having a "garnet-type crystal structure”.
  • the solid electrolyte has a crystal structure in X-ray diffraction that can be recognized as a garnet-type or garnet-like crystal structure by those skilled in the art of solid-state batteries. More specifically, in X-ray diffraction, the solid electrolyte exhibits one or more major peaks corresponding to Miller indices specific to a so-called garnet-type crystal structure (diffraction pattern: ICDD Card No. 01-080-6142).
  • one or more major peaks corresponding to the Miller indices inherent in the so-called garnet-like crystal structure may be attributed to compositional differences. may exhibit one or more major peaks with different angles of incidence (ie, peak positions or diffraction angles) and intensity ratios (ie, peak intensities or diffraction intensity ratios).
  • a typical diffraction pattern of a garnet-like crystal structure for example, ICDD Card No. 00-045-0109 and the like.
  • a solid electrolyte having a garnet-type crystal structure has, for example, general formula (2): It is preferable to have an average chemical composition represented by When the negative electrode layer contains the solid electrolyte having the average chemical composition as described above, it is possible to further improve the capacity retention rate characteristics and interfacial resistance characteristics.
  • A is one or more elements selected from the group consisting of Ga (gallium), Al (aluminum), Mg (magnesium), Zn (zinc), and Sc (scandium).
  • Z is one or more elements selected from the group consisting of Nb (niobium), Ta (tantalum), W (tungsten), Te (tellurium), Mo (molybdenum), and Bi (bismuth).
  • x has a relationship of 0 ⁇ x ⁇ 0.5.
  • y has a relationship of 0 ⁇ y ⁇ 2.0.
  • a is the average valence of A, which is the same as the average valence of A in formula (1).
  • b is the average valence of Z, which is the same as the average valence of Z in formula (1).
  • A is one or more elements selected from the group consisting of Ga and Al.
  • Z is one or more elements selected from the group consisting of Nb, Ta, W, Mo and Bi.
  • x has a relationship of 0.1 ⁇ x ⁇ 0.3.
  • x is a number based on the total number of x for each of those elements.
  • y has a relationship of 0 ⁇ y ⁇ 1.0, preferably 0 ⁇ y ⁇ 0.7. If Z contains more than one element, y is a number based on the total number of y for each of those elements.
  • a is the average valence of A
  • b is the average valence of Z;
  • solid electrolyte represented by the general formula (2) examples include ( Li6.4Ga0.05Al0.15 ) La3Zr2O12 , ( Li6.4Ga0.2 )La 3Zr2O12 , Li6.4La3 ( Zr1.6Ta0.4 ) O12 , ( Li6.4Al0.2 ) La3Zr2O12 , Li6.5La3 ( Zr 1.5Mo0.25 ) O12 .
  • the average chemical composition of the solid electrolyte (particularly the solid electrolyte having a garnet-type crystal structure) in the negative electrode layer means the average value of the chemical compositions of the solid electrolyte in the thickness direction of the negative electrode layer.
  • the average chemical composition of the solid electrolyte is analyzed by breaking the solid battery and using SEM-EDX (energy dispersive X-ray spectroscopy) to analyze the composition by EDX in a field of view that covers the entire thickness direction of the negative electrode layer. and measurable.
  • SEM-EDX energy dispersive X-ray spectroscopy
  • the solid electrolyte of the negative electrode layer can be obtained by the same method as the negative electrode active material except that a raw material compound containing a predetermined metal atom is used, or it can be obtained as a commercial product.
  • the volume ratio of the solid electrolyte (especially the solid electrolyte having a garnet-type crystal structure) in the negative electrode layer is not particularly limited, and from the viewpoint of further improving capacity retention characteristics and interfacial resistance characteristics, it is preferably 10% or more and 50% or less. It is preferably 20% or more and 40% or less.
  • the volume ratio of the solid electrolyte in the negative electrode layer can be measured by the same method as the volume ratio of the negative electrode active material.
  • a garnet-type solid electrolyte is based on the sites where Zr and/or La are detected by EDX and/or WDX.
  • the negative electrode layer may further contain, for example, a sintering aid and a conductive material in addition to the negative electrode active material and solid electrolyte.
  • Sintering aids known in the field of solid-state batteries can be used as the sintering aid. From the viewpoint of further improving capacity retention rate characteristics and interfacial resistance characteristics, as a result of studies by the inventors, the composition of the sintering aid contains at least Li (lithium), B (boron), and O (oxygen), It has been found that the molar ratio of Li to B (Li/B) is preferably 2.0 or more. These sintering aids have a low melting property, and by promoting liquid phase sintering, it becomes possible to densify the negative electrode layer at a lower temperature.
  • sintering aids include Li 3 BO 3 , (Li 2.7 Al 0.3 )BO 3 , Li 2.8 (B 0.8 C 0.2 )O 3 and the like. Among these, it is particularly preferable to use (Li 2.7 Al 0.3 )BO 3 which has particularly high ionic conductivity.
  • the volume ratio of the sintering aid in the negative electrode layer is not particularly limited, and is preferably 0.1% or more and 10% or less, more preferably 1% or more and 7% or less, from the viewpoint of improving battery characteristics.
  • the battery characteristics mean the characteristics of a battery that are required in a field where battery use or power storage is assumed, such as capacity retention rate characteristics and interfacial resistance characteristics.
  • the volume ratio of the sintering aid in the negative electrode layer can be measured by the same method as the volume ratio of the negative electrode active material.
  • B can be noted as an element detected by EDX and/or WDX, which is determined to be the region of the sintering aid.
  • a conductive material known in the field of solid-state batteries can be used as the conductive material in the negative electrode layer.
  • conductive materials preferably used include, for example, Ag (silver), Au (gold), Pd (palladium), Pt (platinum), Cu (copper), Sn (tin), metal materials such as Ni (nickel); and carbon materials such as carbon nanotubes such as acetylene black, ketjen black, Super P (registered trademark), and VGCF (registered trademark).
  • the shape of the carbon material is not particularly limited, and any shape such as spherical, plate-like, and fibrous may be used.
  • As the conductive material it is preferable to use a metal material (especially Ag) from the viewpoint of improving the performance of battery characteristics.
  • the volume ratio of the conductive material in the negative electrode layer is not particularly limited, and from the viewpoint of improving battery characteristics, it is preferably 10% or more and 50% or less, more preferably 20% or more and 40% or less.
  • the volume ratio of the conductive material in the negative electrode layer can be measured by the same method as the volume ratio of the negative electrode active material. From the SEM-EDX and WDX analyses, a portion where only signals of the metal element used can be observed can be regarded as a conductive material.
  • the porosity of the negative electrode layer is not particularly limited, and is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less from the viewpoint of improving battery characteristics.
  • the porosity of the negative electrode layer the value measured from the SEM image after FIB cross-sectional processing is used.
  • the negative electrode layer is a layer that can be called a "negative electrode active material layer".
  • the negative electrode layer may have a so-called negative current collector or negative current collecting layer.
  • the positive electrode layer is not particularly limited in the present invention.
  • the cathode layer includes a cathode active material.
  • the positive electrode layer preferably has the form of a sintered body containing positive electrode active material particles.
  • the positive electrode active material is not particularly limited, and positive electrode active materials known in the field of solid batteries can be used.
  • positive electrode active materials include lithium-containing phosphate compound particles having a Nasicon type structure, lithium-containing phosphate compound particles having an olivine type structure, lithium-containing layered oxide particles, and lithium-containing oxide particles having a spinel type structure. mentioned. Li3V2 ( PO4 ) 3 etc. are mentioned as a specific example of the lithium containing phosphate compound which has a Nasicon type structure preferably used .
  • Specific examples of lithium-containing phosphate compounds having an olivine structure that are preferably used include Li 3 Fe 2 (PO 4 ) 3 and LiMnPO 4 .
  • lithium-containing layered oxide particles that are preferably used include LiCoO 2 and LiCo 1/3 Ni 1/3 Mn 1/3 O 2 .
  • lithium-containing oxides having a spinel structure that are preferably used include LiMn 2 O 4 , LiNi 0.5 Mn 1.5 O 4 , Li 4 Ti 5 O 12 and the like.
  • Lithium-containing layered oxides such as LiCoO 2 and LiCo 1/3 Ni 1/3 Mn 1/3 O 2 are used as positive electrode active materials from the viewpoint of reactivity during co-firing with the LISICON-type solid electrolyte used in the present invention. It is used more preferably. In addition, only one type of these positive electrode active material particles may be used, or a plurality of types may be mixed and used.
  • the positive electrode active material having a Nasicon type structure means that the positive electrode active material (particularly its particles has a Nasicon type crystal structure).
  • the positive electrode active material in the positive electrode layer has a Nasicon type structure
  • the positive electrode active material (particularly its particles) has the following characteristics in X-ray diffraction: It means that one or more major peaks corresponding to the Miller indices specific to the so-called Nasicon type crystal structure are exhibited at a predetermined angle of incidence.
  • Preferably used positive electrode active materials having a Nasicon type structure are exemplified above. compounds that have
  • That the positive electrode active material has an olivine-type structure in the positive electrode layer means that the positive electrode active material (especially particles thereof) has an olivine-type crystal structure. It means having a crystal structure that can be recognized as a type crystal structure. In a narrow sense, that the positive electrode active material in the positive electrode layer has an olivine structure means that the positive electrode active material (particularly its particles) has a Miller index of 1 corresponding to the so-called olivine crystal structure in X-ray diffraction. It means exhibiting more than one major peak at a given angle of incidence. Examples of the positive electrode active material having an olivine structure that is preferably used include the compounds exemplified above.
  • the positive electrode active material having a spinel structure means that the positive electrode active material (especially particles thereof) has a spinel crystal structure. It means having a crystal structure that can be recognized as a type crystal structure. In a narrow sense, when the positive electrode active material in the positive electrode layer has a spinel structure, the positive electrode active material (particularly its particles) has a Miller index of 1 corresponding to the so-called spinel crystal structure in X-ray diffraction. It means exhibiting more than one major peak at a given angle of incidence. Examples of the positive electrode active material having a spinel structure that is preferably used include the compounds exemplified above.
  • the chemical composition of the positive electrode active material may be the average chemical composition.
  • the average chemical composition of the positive electrode active material means the average value of the chemical composition of the positive electrode active material in the thickness direction of the positive electrode layer.
  • the average chemical composition of the positive electrode active material is obtained by breaking the solid battery and using SEM-EDX (energy dispersive X-ray spectroscopy) to perform composition analysis by EDX in a field of view that covers the entire thickness direction of the positive electrode layer. Analytical and measurable.
  • the positive electrode active material can be obtained by the same method as the negative electrode active material, except that a raw material compound containing a predetermined metal atom is used, or it can be obtained as a commercial product.
  • the average particle size of the positive electrode active material is not particularly limited.
  • the average particle size of the positive electrode active material can be obtained by the same method as for the average particle size of the negative electrode active material in the negative electrode layer.
  • the volume ratio of the positive electrode active material in the positive electrode layer is not particularly limited, and from the viewpoint of improving battery characteristics, it is preferably 30% or more and 90% or less, more preferably 40% or more and 70% or less.
  • the positive electrode layer may further contain, for example, a solid electrolyte, a sintering aid, a conductive material, etc., in addition to the positive electrode active material.
  • the type of solid electrolyte contained in the positive electrode layer is not particularly limited.
  • a solid electrolyte having a garnet-type crystal structure for example, a solid electrolyte represented by the general formula (2), particularly (Li 6.4 Ga 0.2 )La 3 Zr 2 O 12 , Li6.4La3 ( Zr1.6Ta0.4 ) O12 , ( Li6.4Al0.2 ) La3Zr2O12 , Li6.5La3 ( Zr1.5Mo0 .25 ) O 12 ), solid electrolytes with a LISICON-type structure (e.g.
  • Li 3+x (V 1-x Si x )O 4 solid electrolytes with a perovskite-type crystal structure (e.g. La 2/3-x Li 3x TiO 3 ), solid electrolytes having an amorphous structure (eg, Li 3 BO 3 —Li 4 SiO 4 ), and the like.
  • a solid electrolyte having a garnet-type crystal structure from the viewpoint of improving battery characteristics.
  • the solid electrolyte of the positive electrode layer can be obtained by the same method as the negative electrode active material except that it uses a raw material compound containing a predetermined metal atom, or it can be obtained as a commercial product.
  • the volume ratio of the solid electrolyte in the positive electrode layer is not particularly limited, and from the viewpoint of improving battery characteristics, it is preferably 20% or more and 60% or less, more preferably 30% or more and 45% or less.
  • the same compound as the sintering aid for the negative electrode layer can be used.
  • the volume ratio of the sintering aid in the positive electrode layer is not particularly limited, and from the viewpoint of improving battery characteristics, it is preferably 0.1% or more and 20% or less, more preferably 1% or more and 10% or less. preferable.
  • the same compound as the conductive material for the negative electrode layer can be used.
  • the volume ratio of the conductive material in the positive electrode layer is not particularly limited, and from the viewpoint of improving battery characteristics, it is preferably 10% or more and 50% or less, more preferably 20% or more and 40% or less.
  • the porosity of the positive electrode layer is not particularly limited, and is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less from the viewpoint of improving battery characteristics.
  • the porosity of the positive electrode layer the value measured by the same method as for the porosity of the negative electrode layer is used.
  • the positive electrode layer is a layer that can be called a "positive electrode active material layer".
  • the positive electrode layer may have a so-called positive current collector or positive current collecting layer.
  • Solid electrolyte layer contains a solid electrolyte.
  • the solid electrolyte contained in the solid electrolyte layer is not particularly limited .
  • Solid electrolytes having a perovskite structure eg, La 2/3-x Li 3x TiO 3
  • solid electrolytes having an amorphous structure eg, Li 3 BO 3 —Li 4 SiO 4
  • the garnet-type solid electrolyte contained in the solid electrolyte layer is the same as the solid electrolyte having a garnet-type crystal structure contained in the negative electrode layer, and is within the same range as the solid electrolyte having a garnet-type crystal structure described in the description of the negative electrode layer. may be selected from When both the solid electrolyte layer and the negative electrode layer contain a solid electrolyte having a garnet-type structure, the solid electrolyte having a garnet-type crystal structure contained in the solid electrolyte layer and the solid electrolyte having a garnet-type crystal structure contained in the negative electrode layer. may have the same chemical composition or may have different chemical compositions from each other.
  • the garnet-type solid electrolyte contained in the solid electrolyte layer is not particularly limited as long as it has a garnet-type crystal structure. It is preferred to have a chemical composition within the composition range. By including the solid electrolyte having the chemical composition in the solid electrolyte layer, it is possible to achieve an improvement in interfacial resistance characteristics between the solid electrolyte and the negative electrode active material.
  • the chemical composition of the solid electrolyte in the solid electrolyte layer may be the average chemical composition.
  • the average chemical composition of the solid electrolyte (especially the solid electrolyte having a garnet-type crystal structure) in the solid electrolyte layer means the average chemical composition of the solid electrolyte in the thickness direction of the solid electrolyte layer.
  • the average chemical composition of the solid electrolyte is obtained by breaking the solid battery and using SEM-EDX (energy dispersive X-ray spectroscopy) to perform composition analysis by EDX in a field of view that covers the entire thickness direction of the solid electrolyte layer. Analytical and measurable.
  • the chemical composition and crystal structure of the solid electrolyte in the solid electrolyte layer usually do not change even after firing.
  • the solid electrolyte preferably has the above-described chemical composition and crystal structure in the solid battery after firing the solid electrolyte layer together with the negative electrode layer and the positive electrode layer.
  • the volume ratio of the solid electrolyte in the solid electrolyte layer is not particularly limited. % or more and 100% or less.
  • the volume ratio of the solid electrolyte in the solid electrolyte layer can be measured by the same method as the volume ratio of the solid electrolyte in the negative electrode layer.
  • the solid electrolyte layer may further contain, for example, a sintering aid in addition to the solid electrolyte.
  • a sintering aid in addition to the solid electrolyte.
  • at least one of the negative electrode layer and the solid electrolyte layer preferably both, preferably further contains a sintering aid.
  • At least one of the negative electrode layer and the solid electrolyte layer further contains a sintering aid means that one of the negative electrode layer and the solid electrolyte layer may further contain a sintering aid, or both of them may contain a sintering aid. It means that it may contain more.
  • the same compound as the sintering aid for the negative electrode layer can be used as the sintering aid for the solid electrolyte layer.
  • the volume ratio of the sintering aid in the solid electrolyte layer is not particularly limited, and is preferably 0.1% or more and 20% or less, and preferably 1% or more and 10% or less, from the viewpoint of improving battery characteristics. more preferred.
  • the thickness of the solid electrolyte layer is usually 0.1 ⁇ m or more and 30 ⁇ m or less, and preferably 1 ⁇ m or more and 20 ⁇ m or less from the viewpoint of thinning the solid electrolyte layer.
  • the thickness of the solid electrolyte layer is the average value of the thicknesses measured at arbitrary 10 points in the SEM image.
  • the porosity is not particularly limited, and is preferably 20% or less, more preferably 15% or less, and still more preferably 10% or less from the viewpoint of improving battery characteristics.
  • the porosity of the solid electrolyte layer the value measured by the same method as for the porosity of the negative electrode layer is used.
  • the solid-state battery of the present invention may further have all the members that conventional solid-state batteries can have, such as a positive electrode current collecting layer, a negative electrode current collecting layer, a protective layer, end face electrodes, and the like.
  • a solid-state battery can be manufactured, for example, by a so-called green sheet method, a printing method, or a combination of these methods.
  • a paste is prepared by appropriately mixing a positive electrode active material or a raw material, a solvent, a resin, and the like that will become the positive electrode active material.
  • the paste is applied on a sheet and dried to form a first green sheet for forming a positive electrode layer.
  • the first green sheet may contain a solid electrolyte, a conductive material and/or a sintering aid.
  • a paste is prepared by appropriately mixing the negative electrode active material or raw materials, solvents, resins, etc. that will become the negative electrode active material.
  • the paste is applied onto the sheet and dried to form a second green sheet for constructing the negative electrode.
  • the second green sheet may contain a solid electrolyte, a conductive material and/or a sintering aid.
  • a paste is prepared by appropriately mixing the solid electrolyte or the raw materials, solvents, resins, etc. that will become the solid electrolyte.
  • the paste is applied and dried to fabricate a third green sheet for forming the solid electrolyte layer.
  • the third green sheet may contain a sintering aid or the like.
  • a laminate is produced by appropriately laminating the first to third green sheets. You may press the produced laminated body. Preferred pressing methods include hydrostatic pressing and the like. After that, the laminate is fired at, for example, 600 to 800° C. to obtain a solid battery.
  • the printing method will be explained.
  • the printing method is the same as the green sheet method except for the following. ⁇ Prepare the paste for each layer so that the blending amount of solvent and resin is suitable for manufacturing by printing method. - Printing and lamination using the paste of each layer to produce a laminate.
  • Lithium hydroxide monohydrate LiOH.H 2 O which is the Li source
  • LiOH.H 2 O Li source
  • a toluene-acetone mixed solvent was added to the obtained calcined powder, and the mixture was pulverized in a planetary ball mill for 6 hours. This pulverized powder was dried to obtain a solid electrolyte powder. It was confirmed by ICP measurement that the composition of the powder was Li 6.4 La 3 Zr 1.6 Ta 0.4 O 12 and that there was no deviation.
  • Examples 4-6 Lithium hydroxide monohydrate LiOH.H 2 O, vanadium pentoxide V 2 O 5 , and germanium oxide GeO 2 were used as raw materials and weighed so as to obtain the chemical composition of the negative electrode active material shown in Examples 4 to 6. Negative electrode active material powders were produced in the same manner as in Examples 1 to 3, except for the above.
  • Example 7-9 Lithium hydroxide monohydrate LiOH.H 2 O, vanadium pentoxide V 2 O 5 , and titanium oxide TiO 2 were used as raw materials and weighed so as to have the chemical composition of the negative electrode active material shown in Examples 7 to 9. Negative electrode active material powders were produced in the same manner as in Examples 1 to 3, except for the above.
  • Negative electrode active material powders were prepared in the same manner as in Examples 1 to 3, except that the powder was weighed so as to have a chemical composition of .
  • Negative electrode active material powders were prepared in the same manner as in Examples 1 to 3, except that lithium hydroxide monohydrate LiOH.H 2 O and vanadium pentoxide V 2 O 5 were used as raw materials.
  • Comparative example 2 A negative electrode active material powder was produced in the same manner as in Examples 1 to 3, except that the raw materials were weighed so as to have the chemical composition of Comparative Example 2.
  • Sintering aid powders used in Examples and Comparative Examples were produced as follows. Lithium hydroxide monohydrate LiOH.H 2 O, boron oxide B2O3, and lithium carbonate Li 2 CO 3 were used as raw materials. Each raw material was appropriately weighed so that the chemical composition would be Li 3 BO 3 with a predetermined chemical composition, mixed well in a mortar, and then calcined at 650° C. for 5 hours. After that, the calcined powder was thoroughly pulverized and mixed again in a mortar, and then fired at 680° C. for 40 hours.
  • a mixed solvent of toluene and acetone was added to the obtained sintered powder, and the powder was pulverized for 6 hours in a planetary ball mill and dried to obtain a sintering aid powder. It was confirmed by ICP measurement that the above powder had no composition deviation.
  • a half-cell was fabricated as follows.
  • Solid electrolyte powder having a garnet-type crystal structure, butyral resin, and alcohol were mixed at a mass ratio of 200:15:140.
  • a solid electrolyte powder was obtained.
  • the solid electrolyte powder coated with the butyral resin was pressed at 90 MPa using a tablet molding machine to form tablets.
  • the resulting solid electrolyte tablet was sufficiently covered with mother powder and fired at a temperature of 500° C. in an oxygen atmosphere to remove the butyral resin, and then fired at about 1200° C. for 3 hours in an oxygen atmosphere. After that, the temperature was lowered to obtain a sintered body of the solid electrolyte.
  • a garnet-type solid electrolyte substrate (solid electrolyte layer) was obtained by polishing the surface of the obtained sintered body.
  • a solid electrolyte powder LLZ having a garnet-type crystal structure and a negative electrode active material powder, a sintering aid powder, and a conductive material powder (Ag particles) having the chemical compositions shown in Table 1 were mixed at a volume ratio of 35:30.
  • a negative electrode layer paste was prepared by weighing and kneading with alcohol and a binder so as to have a ratio of :5:30.
  • the negative electrode layer paste was applied onto the solid electrolyte layer (that is, the solid electrolyte substrate) and dried to obtain a laminate. After removing the binder by heating the laminate to 400° C., the laminate was heat-treated and fired at 800° C.
  • the chemical formulas in Table 1 indicate the average chemical composition of the negative electrode active material.
  • the average chemical composition was measured by the following method. For the average chemical composition, after breaking the half cell and polishing the cross section by ion milling, SEM-WDX (energy dispersive X-ray spectroscopy) was used to analyze 10 points of the negative electrode active material part in the negative electrode layer and WDX point analysis. It was obtained by averaging after quantitative analysis at .
  • composition analysis By performing quantitative analysis (composition analysis) by WDX in a field of view that covers the entire thickness direction of each layer, the average chemical composition of the negative electrode active material and the solid electrolyte in the negative electrode layer, and the solid electrolyte having a garnet-type crystal structure in the solid electrolyte layer
  • the average chemical composition of LLZ was obtained.
  • the composition analysis by JEOL JXA-8530F was used.
  • solid electrolyte layer 10 solid electrolyte sites were quantitatively analyzed by WDX point analysis in the negative electrode layer and the solid electrolyte layer, and then averaged.
  • the chemical formula (Li [7-ax-(b-4)y] A x )La 3 Zr 2-y Z y O 12 before firing It was calculated using the above chemical formula from the information on A and Z charged in , and the information on x and y obtained by composition analysis of WDX.
  • the garnet-type crystal structure was confirmed by X-ray diffraction (XRD measurement) by obtaining an X-ray diffraction image that can be attributed to a garnet-like crystal structure (ICDD Card No. 00-045-0109). Also, the crystal structure of the negative electrode active material in the negative electrode layer was confirmed by performing XRD measurement on the negative electrode layer of the half cell. Comparative Example 1 and Examples 1 to 10 were confirmed by obtaining X-ray diffraction images that could be attributed to the ⁇ -LVO structure, and Comparative Example 2 was attributed to the ⁇ -LVO structure.
  • a current value for charging and discharging was set to 1.0C.
  • charging corresponds to a reduction reaction that inserts lithium ions into the negative electrode active material
  • discharging corresponds to an oxidation reaction that desorbs lithium ions from the negative electrode active material. It was confirmed that in any cell used in the present invention, a reversible capacity of 80% or more of the theoretical value of the charge/discharge capacity was obtained.
  • the initial charge capacity at 0.1C and the initial charge capacity at 1.0C of the produced solid-state battery were measured. This "(capacity at 1.0C charge/capacity at 0.1C charge) x 100" was taken as the 1C capacity retention rate. ⁇ ; 67% ⁇ 1.0C capacity retention rate ⁇ 100% (best); ⁇ ; 50% ⁇ 1.0C capacity retention rate ⁇ 67% (good); ⁇ : 1C capacity retention rate ⁇ 50% (practically problematic).
  • the resistance after 60% charge depth is very high, and the diffusion resistance of Li in the negative electrode active material in this region is particularly high, which is the reason for the low capacity retention rate. (Fig. 2). From the above, it was found that the sample having the ⁇ -Li 3 VO 4 structure exhibits a high capacity retention rate even under high-rate charging, that is, is capable of high-speed charging, and is more preferable.
  • FIG. 1 shows the relationship between the real component (Za) and the imaginary component (Zb) of impedance.
  • the first arc R SE is attributed to the solid electrolyte
  • the second arc R int is attributed to the interfacial resistance between the negative electrode active material and the solid electrolyte LLZ having a garnet-type crystal structure.
  • the resistance was read from the intersection of this arc with the real axis. Further, the product of the area of the negative electrode layer after firing and the resistance value was calculated as the interfacial resistance value. It was confirmed that the interfacial resistance between Li/LLZ was sufficiently smaller ( ⁇ 5 ⁇ cm 2 ) than the Li/LLZ/Li cell produced above. ⁇ ; interfacial resistance ⁇ 67 ⁇ cm 2 (best); ⁇ ; 67 ⁇ cm 2 ⁇ interfacial resistance ⁇ 82 ⁇ cm 2 (excellent) ⁇ ; 82 ⁇ cm 2 ⁇ interfacial resistance ⁇ 150 ⁇ cm 2 (good); ⁇ : Interfacial resistance>150 ⁇ cm 2 (impossible) (problematic in practice).
  • a solid-state battery according to an embodiment of the present invention can be used in various fields where battery use or power storage is assumed.
  • a solid state battery according to an embodiment of the invention can be used in the field of electronics packaging.
  • the solid-state battery according to one embodiment of the present invention is also used in the electric, information, and communication fields where mobile devices are used (for example, mobile phones, smartphones, smart watches, laptops, digital cameras, activity meters, arm computers, Electronic paper, wearable devices, RFID tags, card-type electronic money, electric and electronic equipment fields including small electronic devices such as smart watches, etc.), household and small industrial applications (e.g., electric tools, golf carts, households (e.g., forklifts, elevators, harbor cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trains, electrically assisted bicycles, electric motorcycles, etc.), power system applications (for example, various power generation, road conditioners, smart grids, general household electrical storage systems, etc.), medical applications (medical equipment such as earphone hearing aids), pharmaceutical

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