Classifications

• • 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
  • H01B1/10—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances sulfides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/02—Preparation of sulfur; Purification
  • C01B17/0237—Converting into particles, e.g. by granulation, milling
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/14—Sulfur, selenium, or tellurium compounds of phosphorus
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
• • 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
  • H01M10/056—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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C19/00—Other disintegrating devices or methods
  • B02C19/0056—Other disintegrating devices or methods specially adapted for specific materials not otherwise provided for
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • 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
  • C01P2006/12—Surface area
• • 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
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
• • 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 method for pulverizing a sulfur compound, a method for pulverizing a solid electrolyte, a method for producing a solid electrolyte, and a solid electrolyte.
• solid-state batteries which use solid electrolytes instead of electrolytes and do not contain flammable organic solvents, are expected to be put into practical use as batteries that are both safe and have high energy density.
• Solid electrolytes In order to realize solid-state batteries, solid electrolytes are being actively developed. Solid electrolytes generally have lower ionic conductivity than organic electrolytes, making it difficult to put them into practical use.
• a solid electrolyte can be obtained by mixing and firing predetermined raw materials to obtain crystalline solid electrolyte raw material powder, and then pulverizing the powder using a bead mill or the like (Patent Documents 1 to 3).
• an object of the present invention is to provide a solid electrolyte powder with excellent ionic conductivity.
• the present inventors devised a pulverization method and conducted the pulverization so that the particle size of the solid electrolyte before and after pulverization satisfies a predetermined relationship. It was discovered that the desired solid electrolyte powder could be obtained.
• the present invention provides a pulverization method for pulverizing sulfur compounds, comprising:
• the present invention provides a method for pulverizing sulfur compounds that satisfies the relationship shown in formula (1) below.
• D2/D1 ⁇ 0.49 (1) (In the formula, D1 represents the median diameter of the unpulverized sulfur compound when the pulverization method has only one pulverization step. Also, when the pulverization method has two or more pulverization steps, D1 represents the median diameter of the unpulverized sulfur compound. It represents the median diameter of the sulfur compound before the pulverization step in the pulverization step.
• D2 represents the median diameter of the sulfur compound after pulverization when the pulverization method includes only one pulverization step. When the pulverization method has two or more pulverization steps, it represents the median diameter of the sulfur compound after performing the pulverization step in any of the pulverization steps. )
• the present invention also provides a pulverization method for pulverizing sulfur compounds, comprising:
• the present invention provides a method for pulverizing sulfur compounds that satisfies the relationship shown in formula (2) below.
• A/B ⁇ 3.6 ⁇ 10-3 (2) In the formula, A (S/cm) is the ionic conductivity (S/cm) of the sulfur compound after the pulverization step and the ion of the unpulverized sulfur compound when the pulverization method has only one pulverization step.
• the pulverization method has two or more pulverization steps, the ionic conductivity of the sulfur compound before any pulverization step and the difference between the ion conductivity of the sulfur compound before the pulverization step and the pulverization step It represents the difference from the ionic conductivity of the sulfur compound.
• B ( ⁇ m) represents the difference between the median diameter ( ⁇ m) of the unpulverized sulfur compound and the median diameter ( ⁇ m) of the sulfur compound after the pulverization step when the pulverization method has only one pulverization step. .
• the median diameter ( ⁇ m) of the sulfur compound before the arbitrary pulverization step and the median diameter ( ⁇ m) of the sulfur compound after the arbitrary pulverization step are performed. represents the difference between )
• the present invention includes a preparation step of preparing a solid electrolyte; a pulverizing step of pulverizing the solid electrolyte,
• the purpose of the present invention is to provide a method for pulverizing a solid electrolyte in which the pulverizing step satisfies the relationship shown in equation (3) below.
• D4/D3 ⁇ 0.49 (3) (In the formula, D3 represents the median diameter of the unpulverized solid electrolyte when the pulverization step is performed only once. Also, when the pulverization step is performed two or more times, the pulverization step is performed in any pulverization step.
• D4 represents the median diameter of the solid electrolyte after pulverization when the pulverization step is performed only once.D4 represents the median diameter of the solid electrolyte after pulverization when the pulverization step is performed two or more times. It represents the median diameter of the solid electrolyte after the pulverization process.
• the present invention also includes a preparation step of preparing a solid electrolyte; a pulverizing step of pulverizing the solid electrolyte,
• the purpose of the present invention is to provide a method for pulverizing a solid electrolyte in which the pulverizing step satisfies the relationship shown in equation (4) below.
• C/D ⁇ 3.6 ⁇ 10-3 (4)
• C (S/cm) is the ionic conductivity (S/cm) of the solid electrolyte after the pulverization step and the ionic conductivity (S/cm) of the unpulverized solid electrolyte when the pulverization step is performed only once.
• the ionic conductivity (S/cm) of the solid electrolyte before any pulverization process and the ion conductivity (S/cm) of the solid electrolyte after the pulverization process It represents the difference from conductivity (S/cm).
• D ( ⁇ m) represents the difference between the median diameter ( ⁇ m) of the unpulverized solid electrolyte and the median diameter ( ⁇ m) of the solid electrolyte after the pulverization step when the pulverization step is performed only once.
• the median diameter ( ⁇ m) of the solid electrolyte before the arbitrary pulverization step and the median diameter ( ⁇ m) of the solid electrolyte after the arbitrary pulverization step are performed. represents the difference between )
• the present invention provides a method for producing a solid electrolyte, which includes the step of pulverizing solid electrolyte mother powder
• the purpose of the present invention is to provide a method for manufacturing a solid electrolyte in which the pulverization step satisfies the relationship shown in equation (5) below.
• D6/D5 ⁇ 0.49 (5) (In the formula, D5 represents the median diameter of the mother powder when the pulverization process is performed only once. Also, when the pulverization process is performed two or more times, D5 represents the median diameter of the solid electrolyte before any pulverization process. represent. D6 represents the median diameter of the solid electrolyte after the pulverization step when the pulverization step is performed only once. When the above-mentioned pulverization process is performed twice or more, it represents the median diameter of the solid electrolyte after the above-mentioned arbitrary pulverization process. )
• the present invention also provides a method for producing a solid electrolyte, comprising the step of pulverizing solid electrolyte mother powder,
• the purpose of the present invention is to provide a method for manufacturing a solid electrolyte in which the pulverization step satisfies the relationship shown in equation (6) below.
• E/F ⁇ 3.6 ⁇ 10-3 (6) In the formula, E (S/cm) is the ionic conductivity (S/cm) of the solid electrolyte after the pulverization step and the ionic conductivity (S/cm) of the unpulverized solid electrolyte when the pulverization step is performed only once.
• the ionic conductivity (S/cm) of the solid electrolyte before any pulverization process and the ion conductivity (S/cm) of the solid electrolyte after the pulverization process It represents the difference from conductivity (S/cm).
• F ( ⁇ m) represents the difference between the median diameter ( ⁇ m) of the unpulverized solid electrolyte and the median diameter ( ⁇ m) of the solid electrolyte after the pulverization step when the pulverization step is performed only once.
• the difference between the median diameter ( ⁇ m) of the solid electrolyte before the above-mentioned arbitrary pulverization process and the median diameter ( ⁇ m) of the solid electrolyte after the above-mentioned arbitrary pulverization process is calculated. represent. )
• the value of S1 with respect to S2 is , less than 4.5.
• the present invention will be described below based on its preferred embodiments.
• the pulverization method of the present invention includes a preparation step of preparing a solid electrolyte, and a pulverization step of pulverizing the solid electrolyte, and is characterized in that the pulverization step satisfies the relationship shown in equation (3) below. shall be.
• D4/D3 ⁇ 0.49 (3) In the formula, D3 represents the median diameter ( ⁇ m) of the unpulverized solid electrolyte when the above-mentioned pulverization step is performed only once.
• the pulverization in any pulverization step It represents the median diameter ( ⁇ m) of the solid electrolyte before performing the process.
• D4 represents the median diameter ( ⁇ m) of the solid electrolyte after pulverization when the pulverization step is performed only once.
• the pulverization process is performed twice or more, it represents the median diameter ( ⁇ m) of the solid electrolyte immediately after performing the pulverization process in the arbitrary pulverization process.
• a solid electrolyte is prepared.
• the solid electrolyte include a sulfide solid electrolyte, an oxide solid electrolyte, a nitride solid electrolyte, and a halide solid electrolyte.
• a sulfide solid electrolyte which is a solid electrolyte containing sulfur (S) element, is preferable.
• the sulfide solid electrolyte may, for example, contain lithium (Li) element and sulfur (S) element and have lithium ion conductivity, or may contain lithium (Li) element, phosphorus (P) element and sulfur ( S) may contain the element and have lithium ion conductivity.
• the sulfide solid electrolyte may be a crystalline material, glass ceramics, or glass.
• the sulfide solid electrolyte may have an argyrodite crystal structure.
• Examples of the sulfide solid electrolyte include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiX (X represents one or more halogen elements), Li 2 SP 2 S 5 -P 2 O 5 , Li 2 S-Li 3 PO 4 -P 2 S 5 , Li 3 PS 4 , Li 4 P 2 S 6 , Li 10 GeP 2 S 12 , Li 3.25 Ge 0.25 P 0. 75 S 4 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , Li a PS b X c (X represents at least one halogen element.
• a is 3.0 or more and 6.0 or less
• b represents a number of 3.5 or more and 4.8 or less
• c represents a number of 0.1 or more and 3.0 or less.
• examples include sulfide solid electrolytes described in International Publication No. 2013/099834 pamphlet and International Publication No. 2015/001818 pamphlet.
• a sulfide solid electrolyte When a sulfide solid electrolyte is used as the solid electrolyte, it is preferable to use as raw materials a compound of a Li element source, a P element source compound, an S element source, and, if necessary, a compound of an X element source.
• a compound of a Li element source Li element source compound
• a P element source compound for example, diphosphorus pentasulfide (P 2 S 5 ) can be used.
• the S element source compound when the Li element source compound and/or the P element source compound is a sulfide, the sulfide can be used as the S element source compound.
• LiX can be used as the X element source compound.
• the above raw materials are mixed so that Li element, P element, S element, and if necessary X element become a predetermined molar ratio.
• Mixing is performed using a jet mill, ball mill, rod mill, vibrating ball mill, planetary mill, disc mill, etc.
• the raw material composition obtained by mixing is fired, for example, in an inert gas atmosphere, such as a nitrogen atmosphere or an argon atmosphere.
• an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.
• the raw material composition when it is a sulfide, it may be fired in a hydrogen sulfide gas atmosphere.
• the firing temperature is, for example, preferably 300°C or higher, more preferably 350°C or higher, and even more preferably 400°C or higher.
• the firing temperature is preferably, for example, 700°C or lower, more preferably 600°C or lower, and even more preferably 550°C or lower.
• the firing time is preferably 0.5 hours or more, more preferably 2 hours or more, and even more preferably 3 hours or more.
• the firing time is preferably 20 hours or less, more preferably 10 hours or less, and even more preferably 5 hours or less.
• the fired product is crushed using a mortar and pestle, a ball mill, etc. to obtain a crushed product.
• the crushed material is preferably pre-pulverized before being subjected to main pulverization to form a solid electrolyte powder of a predetermined size (median diameter D3).
• pre-pulverization may be performed.
• the main pulverization may be performed and the preliminary pulverization may be omitted.
• the "median diameter” refers to the volume cumulative particle diameter D 50 at a cumulative volume of 50% by volume, measured by a laser diffraction scattering particle size distribution measurement method.
• Pre-pulverization can be performed wet or dry.
• Various media mills can be used for preliminary grinding.
• a ball mill, bead mill, paint shaker, homogenizer, etc. can be used.
• the grinding media used in the media mill balls and beads made of various ceramics including alumina and zirconia are used.
• the diameter of the grinding media can be, for example, 0.1 mm or more and 50 mm or less.
• organic solvent When carrying out the wet grinding process, it is preferable to use an organic solvent as a dispersion medium because it can suppress the generation of hydrogen sulfide gas caused by the reaction between the solid electrolyte and water.
• organic solvents include aromatic organic solvents such as toluene, xylene, benzene, and solvent naphtha, and aliphatic organic solvents such as heptane, decane, normal hexane, cyclohexane, and mineral spirits. These organic solvents can be used alone or in combination of two or more.
• the solid electrolyte powder having a median diameter of D3 ( ⁇ m) obtained by preliminary pulverization is preferably pulverized (main pulverization) by wet pulverization until it has a median diameter of D4 ( ⁇ m).
• the pulverization process needs to be performed so as to satisfy the following formula (3).
• D4/D3 preferably satisfies the relationship D4/D3 ⁇ 0.45, more preferably satisfies the relationship D4/D3 ⁇ 0.4, and satisfies the relationship D4/D3 ⁇ 0.3. It is more preferable to do so.
• D4/D3 preferably satisfies the relationship 0.05 ⁇ D4/D3, more preferably satisfies the relationship 0.1 ⁇ D4/D3, and the relationship 0.15 ⁇ D4/D3. It is more preferable that the following conditions are satisfied. This makes it possible to provide solid electrolyte powder with excellent ionic conductivity.
• D3 represents the median diameter of the unpulverized solid electrolyte when the pulverization step is performed only once.
• D4 represents the median diameter of the solid electrolyte immediately after pulverization when the pulverization step is performed only once.
• the value t/m of the pulverization time t (minutes) with respect to the weight m (g) is greater than 0, for example. is preferred.
• t/m is preferably less than 2.3, more preferably 1.5 or less, and even more preferably 0.7 or less. This makes it possible to provide solid electrolyte powder with better ionic conductivity.
• the main pulverization may be performed so as to satisfy the relationship shown in equation (4) below.
• C/D ⁇ 3.6 ⁇ 10-3 (4)
• C (S/cm) is the ionic conductivity ⁇ of the solid electrolyte immediately after the pulverization process, ⁇ C1 (S/cm), and the ionic conductivity ⁇ of the unpulverized solid electrolyte, when the pulverization process is performed only once. It represents the difference ( ⁇ C1 - ⁇ C2 ) from C2 (S/cm).
• the ionic conductivity of the solid electrolyte before any pulverization process ⁇ C3 (S/cm) and It represents the difference ( ⁇ C3 ⁇ C4 ) from the ionic conductivity ⁇ C4 (S/cm) of the solid electrolyte immediately after the arbitrary pulverization process.
• D ( ⁇ m) is the difference (d D1 ) between the median diameter d D1 ( ⁇ m) of the unpulverized solid electrolyte and the median diameter d D2 ( ⁇ m) of the solid electrolyte immediately after the pulverization step, when the pulverization step is performed only once. -d D2 ).
• the median diameter d D3 ( ⁇ m) of the solid electrolyte before any pulverization process and the median diameter d D4 ( ⁇ m) of the solid electrolyte immediately after the arbitrary pulverization process is performed. represents the difference (d D3 ⁇ d D4 ).
• the term "ion conductivity" refers to a value measured at 25°C.
• Equation (3) defines the conditions for main pulverization of a solid electrolyte by focusing on the median diameter, which is a direct pulverization condition, whereas equation (4) defines the conditions for main pulverization of a solid electrolyte.
• the conditions are defined by paying attention not only to the median diameter but also to ionic conductivity, which is the desired physical property.
• C/D in equation (4) satisfies the relationship 0 ⁇ C/D, for example.
• the reason why the ionic conductivity of the solid electrolyte powder is improved by adopting the above-mentioned pulverization conditions, that is, formulas (3) and (4) is that the solid electrolyte powder is made finer and the contact area between the solid electrolyte powders is increased. increases, ionic volume conductivity improves, and the proportion of fine powder that does not contribute to volume conductivity decreases, suppressing the increase in the solid electrolyte powder interface, which is the cause of decreases in ionic conductivity. It's for a reason.
• the pulverization is preferably carried out at, for example, 25°C or lower, more preferably 15°C or lower, and even more preferably 5°C or lower.
• pulverization is preferably carried out at -15°C or higher, more preferably at -10°C or higher. This suppresses the agglomeration of the solid electrolyte powder, makes the solid electrolyte powder finer, and further improves the ionic conductivity by increasing the volume conductivity. Increase can be suppressed.
• the temperature is the temperature of the refrigerant flowing through the jacket part of the crusher.
• the diameter of the grinding media used in the main grinding is preferably 0.1 mm or more, for example.
• the diameter of the grinding media is preferably, for example, 50 mm or less, more preferably 10 mm or less, and even more preferably 1.0 mm or less.
• the concentration of the solid electrolyte powder contained in the slurry is preferably set to, for example, 5% by mass or more and 50% by mass or less, from the viewpoint of successfully obtaining solid electrolyte powder with high lithium ion conductivity.
• the ratio of grinding media to slurry is, for example, 5 parts by mass or more and 50 parts by mass or less of grinding media per 100 parts by mass of slurry. This is preferable because the solid electrolyte powder constituting the solid electrolyte powder can be easily obtained.
• It is preferable to set the dispersion time by the media mill to generally 0.1 hour or more and 60 hours or less, particularly 0.5 hour or more and 60 hours or less, since solid electrolyte powder with high lithium ion conductivity can be easily obtained.
• the pulverized solid electrolyte obtained as described above has a specific surface area of S1 (m 2 /g) measured by the BET method, and a ratio calculated from the particle size distribution.
• S1 m 2 /g
• S1/S2 is less than 4.5.
• the ratio S1/S2 is, for example, preferably 4.2 or less, more preferably 3.9 or less, and even more preferably 3.5 or less.
• the ratio S1/S2 may be larger than 0, may be 0.5 or more, or may be 1.0 or more, for example.
• the specific surface area S1 measured by the BET method is a physical quantity indicating the entire surface area including the main body of the solid electrolyte powder described above and fine powder that does not contribute to the ionic conductivity.
• the specific surface area calculated from the particle size distribution is a physical quantity indicating the specific surface area of the solid electrolyte powder that does not contain the fine powder. Therefore, a small value of S1/S2 means that the proportion of fine powder that does not contribute to ionic conductivity is small. Therefore, it is understood from the physical property values that the solid electrolyte powder obtained by the above-described pulverization method has a dominant volume conductivity and exhibits high ionic conductivity.
• the solid electrolyte powder preferably has a volume cumulative particle diameter D 90 of, for example, less than 40 ⁇ m, more preferably 30 ⁇ m or less, and less than 5.9 ⁇ m at a cumulative volume of 90% by laser diffraction scattering particle size distribution measurement method. It is more preferably 5.0 ⁇ m or less, even more preferably 4.0 ⁇ m or less.
• the volume cumulative particle size D 90 is preferably 0.7 ⁇ m or more, and more preferably 1.0 ⁇ m or more, for example.
• the ratio of the ionic conductivity (S/cm) to the median diameter D 50 ( ⁇ m) of the solid electrolyte powder is preferably larger than 1.3 x 10 -3 , and preferably larger than 2.0 x 10 -3 , for example. More preferably, it is 2.5 ⁇ 10 ⁇ 3 or more, even more preferably 3.0 ⁇ 10 ⁇ 3 or more.
• the ratio of ionic conductivity (S/cm) to median diameter D 50 ( ⁇ m) is preferably, for example, 1.0 or less, and more preferably 0.1 or less.
• the ratio of the crystallite size ( ⁇ ) of the solid electrolyte to the median diameter D 50 ( ⁇ m) of the solid electrolyte powder is, for example, preferably 325 or more, more preferably 330 or more, and even more preferably 400 or more. It is preferably 750 or more, and more preferably 750 or more. On the other hand, the ratio of the crystallite size ( ⁇ ) of the solid electrolyte to the median diameter D 50 ( ⁇ m) of the solid electrolyte powder may be, for example, 1200 or less, or 900 or less. Since the crystallite size of the solid electrolyte is large, the interface between crystal grains is reduced, so that the volume conductivity further increases and it becomes possible to provide a solid electrolyte powder having high ionic conductivity.
• the solid electrolyte powder of the present invention thus obtained can be used, for example, as a material constituting a solid electrolyte layer or as a material included in an electrode mixture containing an active material. Specifically, it can be used as a positive electrode mixture constituting a positive electrode layer containing a positive electrode active material, or as a negative electrode mixture constituting a negative electrode layer containing a negative electrode active material. Therefore, the solid electrolyte powder of the present invention can be used in batteries having a solid electrolyte layer, so-called solid batteries. More specifically, it can be used for lithium solid state batteries.
• the lithium solid battery may be a primary battery or a secondary battery, but is preferably used as a lithium secondary battery.
• Solid battery refers to solid batteries that do not contain any liquid or gel material as an electrolyte, as well as solid batteries that contain, for example, 50% by mass or less, 30% by mass or less, or 10% by mass or less of a liquid or gel material as an electrolyte. Embodiments are also included.
• the solid electrolyte layer in a solid battery can be formed, for example, by dropping a slurry containing the solid electrolyte powder of the present invention, a binder, and a solvent onto a substrate and scraping it off with a doctor blade, or by bringing the slurry into contact with the substrate and cutting it with an air knife. It can be manufactured by forming a coating film using a screen printing method or the like, and then removing the solvent through heating and drying. Alternatively, the solid electrolyte powder of the present invention can be press-molded and then processed as appropriate. The solid electrolyte layer may contain other solid electrolyte powders in addition to the solid electrolyte powder of the present invention.
• the thickness of the solid electrolyte layer in the present invention is typically preferably 5 ⁇ m or more and 300 ⁇ m or less, more preferably 10 ⁇ m or more and 100 ⁇ m or less.
• the solid electrolyte layer containing the solid electrolyte powder of the present invention preferably has a porosity of, for example, 50% or less, particularly 30% or less, and even more preferably 20% or less. preferable.
• the porosity of the solid electrolyte layer can be adjusted, for example, by the pressing pressure when forming the solid electrolyte powder of the present invention into a green compact. It is preferable that the press pressure is, for example, 20 MPa or more.
• the solid battery has a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, and it is preferable that the solid electrolyte layer contains the solid electrolyte of the present invention.
• the shape of the solid-state battery include a laminate type, a cylindrical type, and a square type.
• the positive electrode mixture in a solid battery containing the solid electrolyte powder of the present invention includes a positive electrode active material.
• a positive electrode active material for example, those used as positive electrode active materials of lithium secondary batteries can be used as appropriate.
• the positive electrode active material include spinel-type lithium transition metal compounds, lithium metal oxides with a layered structure, and the like.
• the positive electrode mixture may contain other materials such as a conductive additive.
• the negative electrode mixture in a solid battery containing the solid electrolyte powder of the present invention includes a negative electrode active material.
• a negative electrode active material for example, a negative electrode mixture used as a negative electrode active material of lithium secondary batteries can be used as appropriate.
• negative electrode active materials include lithium metal, artificial graphite, natural graphite, carbon materials such as non-graphitizable carbon (hard carbon), lithium titanate, titanium niobium composite oxide, silicon, silicon compounds, tin, and tin compounds. can be mentioned.
• the negative electrode mixture may contain other materials such as a conductive additive.
• the sulfur compound may be any compound containing the sulfur (S) element, and preferably a compound containing at least one of the lithium (Li) element, the phosphorus (P) element, and the halogen (X) element.
• the X element can be at least one of fluorine (F) element, chlorine (Cl) element, bromine (Br) element, and iodine (I) element.
• D1 represents the median diameter ( ⁇ m) of the unpulverized sulfur compound when the pulverizing method has only one pulverizing step.
• D2 represents the median diameter ( ⁇ m) of the sulfur compound immediately after pulverization when the pulverization method includes only one pulverization step.
• the pulverization method has two or more pulverization steps, it represents the median diameter ( ⁇ m) of the sulfur compound immediately after performing the pulverization step in any of the pulverization steps.
• A/B ⁇ 3.6 ⁇ 10-3 (2)
• a (S/cm) is the ionic conductivity ⁇ A1 (S/cm) of the sulfur compound immediately after the pulverization step and the unpulverized sulfur compound when the pulverization method has only one pulverization step. It represents the difference ( ⁇ A1 - ⁇ A2 ) from the ionic conductivity ⁇ A2 (S/cm) of It represents the difference ( ⁇ A3 ⁇ A4 ) between the conductivity ⁇ A3 (S/cm) and the ionic conductivity ⁇ A4 (S/cm) of the sulfur compound immediately after performing the arbitrary pulverization step.
• B is the difference between the median diameter dB1 ( ⁇ m) of the unpulverized sulfur compound and the median diameter dB2 ( ⁇ m) of the sulfur compound immediately after the pulverization step, when the pulverization method has only one pulverization step.
• d B1 ⁇ d B2 the median diameter d B3 ( ⁇ m) of the sulfur compound before the arbitrary pulverization step and the median diameter d of the sulfur compound immediately after the arbitrary pulverization step are performed.
• B4 ( ⁇ m) represents the difference (d B3 - d B4 ).
• the present invention can also apply the above-described solid electrolyte pulverization method to a solid electrolyte manufacturing method.
• the method for producing a solid electrolyte includes the steps of producing solid electrolyte mother powder using predetermined raw materials and pulverizing the solid electrolyte mother powder.
• formulas (3) and (4) in the solid electrolyte pulverization method described above are represented by formulas (5) and (6) below.
• D6/D5 ⁇ 0.49 (5) In the formula, D5 represents the median diameter ( ⁇ m) of the mother powder when the pulverization process is performed only once. Also, when the pulverization process is performed two or more times, the It represents the median diameter ( ⁇ m) of the solid electrolyte.
• D6 represents the median diameter ( ⁇ m) of the solid electrolyte immediately after pulverization when the pulverization is performed only once. When the pulverization step is performed twice or more, it represents the median diameter ( ⁇ m) of the solid electrolyte immediately after the pulverization in the arbitrary pulverization. )
• E/F ⁇ 3.6 ⁇ 10-3 (6) (In the formula, E (S/cm) is the ionic conductivity ⁇ E1 (S/cm) of the solid electrolyte immediately after the pulverization process and the ionic conductivity of the unpulverized solid electrolyte when the pulverization process is performed only once. It represents the difference ( ⁇ E1 - ⁇ E2 ) from ⁇ E2 (S/cm).
• the median diameter d F3 ( ⁇ m) of the solid electrolyte before the arbitrary pulverization step and the median diameter d of the solid electrolyte immediately after the arbitrary pulverization step are performed. It represents the difference (d F3 - d F4 ) from F4 ( ⁇ m).
• the sulfur compound has lithium ion conductivity.
• lithium ion conductivity refers to having a function as an electrolyte used in lithium ion batteries.
• the sulfur compound has a lithium ion conductivity of 4.0 mS/cm or more at room temperature, that is, 25° C., and in particular, a lithium ion conductivity of 4.2 mS/cm or more. is preferable, and it is particularly preferable to have a lithium ion conductivity of 5.0 mS/cm or more, and more preferably 5.5 mS/cm or more and 6.0 mS/cm or more. Lithium ion conductivity can be measured using the method described in Examples below.
• a pulverization method for pulverizing a sulfur compound A method for pulverizing a sulfur compound that satisfies the relationship shown in formula (1) below.
• D2/D1 ⁇ 0.49 (1) (In the formula, D1 represents the median diameter of the unpulverized sulfur compound when the pulverization method has only one pulverization step. Also, when the pulverization method has two or more pulverization steps, D1 represents the median diameter of the unpulverized sulfur compound. It represents the median diameter of the sulfur compound before the pulverization step in the pulverization step. D2 represents the median diameter of the sulfur compound after pulverization when the pulverization method includes only one pulverization step.
• the pulverization method When the pulverization method has two or more pulverization steps, it represents the median diameter of the sulfur compound after performing the pulverization step in any of the pulverization steps.
• the grinding time of the sulfur compound is t (minutes) and the weight of the sulfur compound is m (g)
• the value of t (minutes) relative to the m (g) is greater than 0 and less than 2.3.
• the method for pulverizing a sulfur compound according to [1].
• a pulverization method for pulverizing a sulfur compound A method for pulverizing a sulfur compound that satisfies the relationship shown in formula (2) below.
• a (S/cm) is the ionic conductivity (S/cm) of the sulfur compound after the pulverization step and the ion of the unpulverized sulfur compound when the pulverization method has only one pulverization step. It represents the difference between the conductivity (S/cm) and the sulfur compound's ionic conductivity (S/cm) before any pulverization process when the pulverization method has two or more pulverization steps. It represents the difference from the ionic conductivity (S/cm) of the sulfur compound after the pulverization process.
• B ( ⁇ m) represents the difference between the particle size ( ⁇ m) of the unpulverized sulfur compound and the median diameter ( ⁇ m) of the sulfur compound after the crushing step, when the pulverization method has only one pulverization step. .
• the median diameter ( ⁇ m) of the sulfur compound before the arbitrary pulverization step and the median diameter ( ⁇ m) of the sulfur compound after the arbitrary pulverization step are performed. represents the difference between ) [4]
• D4/D3 ⁇ 0.49 (3) (In the formula, D3 represents the median diameter of the unpulverized solid electrolyte when the pulverization step is performed only once. Also, when the pulverization step is performed two or more times, the pulverization step is performed in any pulverization step.
• D4 represents the median diameter of the solid electrolyte after pulverization when the pulverization step is performed only once.D4 represents the median diameter of the solid electrolyte after pulverization when the pulverization step is performed two or more times. It represents the median diameter of the solid electrolyte after the pulverization process.)
• C/D ⁇ 3.6 ⁇ 10-3 (4) (In the formula, C (S/cm) is the ionic conductivity (S/cm) of the solid electrolyte after the pulverization step and the ionic conductivity (S/cm) of the unpulverized solid electrolyte when the pulverization step is performed only once.
• the ionic conductivity (S/cm) of the solid electrolyte before any pulverization process and the ion conductivity (S/cm) of the solid electrolyte after the pulverization process Represents the difference between conductivity and (S/cm).
• D ( ⁇ m) is the median diameter ( ⁇ m) of the unpulverized solid electrolyte and the median diameter of the solid electrolyte after the pulverization step when the pulverization step is performed only once.
• the median diameter ( ⁇ m) of the solid electrolyte before the arbitrary pulverization step and the difference between the median diameter ( ⁇ m) of the solid electrolyte before the arbitrary pulverization step It represents the difference from the median diameter ( ⁇ m) of the solid electrolyte.
• a method for producing a solid electrolyte comprising the step of pulverizing solid electrolyte mother powder, A method for producing a solid electrolyte, wherein the pulverizing step satisfies the relationship shown in the following formula (5).
• D6/D5 ⁇ 0.49 (5) In the formula, D5 represents the median diameter of the mother powder when the pulverization process is performed only once. Also, when the pulverization process is performed two or more times, D5 represents the median diameter of the solid electrolyte before any pulverization process. represent. D6 represents the median diameter of the solid electrolyte after the pulverization step when the pulverization step is performed only once.
• a method for producing a solid electrolyte comprising the step of pulverizing solid electrolyte mother powder, A method for producing a solid electrolyte, wherein the pulverizing step satisfies the relationship shown in equation (6) below.
• E/F ⁇ 3.6 ⁇ 10-3 (6) In the formula, E (S/cm) is the ionic conductivity (S/cm) of the solid electrolyte after the pulverization step and the ionic conductivity (S/cm) of the unpulverized solid electrolyte when the pulverization step is performed only once.
• the ionic conductivity (S/cm) of the solid electrolyte before any pulverization process and the ion conductivity (S/cm) of the solid electrolyte after the pulverization process It represents the difference from conductivity (S/cm).
• F ( ⁇ m) represents the difference between the median diameter ( ⁇ m) of the unpulverized solid electrolyte and the median diameter ( ⁇ m) of the solid electrolyte after the pulverization step when the pulverization step is performed only once.
• the solid electrolyte according to [12] which has a volume cumulative particle size D 90 of less than 5.9 ⁇ m at a cumulative volume of 90% by volume measured by a laser diffraction scattering particle size distribution measurement method.
• the value of the conductivity (S/cm) with respect to the volume cumulative particle diameter D 50 ( ⁇ m) at 50 volume % cumulative volume by laser diffraction scattering particle size distribution measurement method is larger than 1.3 ⁇ 10 -3 , [12] ] or the solid electrolyte according to [13].
• the value of crystallite size ( ⁇ ) with respect to volume cumulative particle diameter D 50 ( ⁇ m) at 50 volume % cumulative volume measured by laser diffraction scattering particle size distribution measurement method is 325 or more, [12] to [14] The solid electrolyte described in any one of the above. [16] The solid electrolyte according to any one of [12] to [15], wherein the solid electrolyte contains a lithium (Li) element, a phosphorus (P) element, and a sulfur (S) element.
• Example 1 Li 2 S powder, P 2 S 5 powder, LiCl powder, and LiBr powder were weighed so that the composition was Li 5.4 PS 4.4 Cl 0.8 Br 0.8 . These powders were ground and mixed using a ball mill to obtain a mixed powder. The mixed powder was fired to obtain a fired product made of lithium ion conductive sulfide. Firing was performed using a tubular electric furnace. During firing, 100% pure hydrogen sulfide gas was passed through the electric furnace at 3.0 L/min. The firing temperature was set at 490°C, and firing was performed for 4 hours. As a result of XRD measurement, it was confirmed that this fired product had a crystal phase having an argyrodite crystal structure.
• the fired product was pre-pulverized by a general method to obtain a solid electrolyte with a median diameter D50 of about 3 ⁇ m, and then the crushed product was mixed with an organic solvent to form a slurry with a concentration of 15% by mass.
• This slurry was subjected to wet pulverization (main pulverization) using a bead mill device ("First Mill" manufactured by Ashizawa Finetech Co., Ltd.).
• the beads used in the bead mill device were made of alumina and had a diameter of 0.2 mm, and a refrigerant at 0° C. was flowed through the jacket of the device.
• toluene was used as an organic solvent.
• the slurry was separated into solid and liquid, and the solid content was dried.
• the dried baked product was sieved through a sieve with an opening of 53 ⁇ m to obtain the desired solid electrolyte powder.
• other conditions such as energy were appropriately selected according to the intended solid electrolyte powder.
• the median diameter D50 , particle diameter D90 , specific surface area, crystallite size, ionic conductivity, and particle size change of the solid electrolyte powder were measured under the following conditions.
• the flow rate of the measurement sample containing a solid electrolyte was set to 50%, and the flow rate of the measurement sample containing a solid electrolyte was set to 50%.
• the sample was irradiated with 30W ultrasonic waves for 60 seconds. Thereafter, the particle size distribution was measured using a laser diffraction particle size distribution analyzer "MT3000II" manufactured by Microtrac Bell Co., Ltd. From the obtained volume-based particle size distribution chart, the cumulative volume was 50% by volume and 90% by volume. The particle sizes were determined and designated as D50 and D90 , respectively.
• the organic solvent was passed through a 60 ⁇ m filter, the solvent refractive index was 1.50, the particle permeability condition was "transmission”, the particle refractive index was 1.59, and the shape was "non-spherical".
• the measurement range was 0.133 ⁇ m to 704.0 ⁇ m, the measurement time was 10 seconds, the measurement was performed twice, and the average values of the obtained measurement values were taken as D 50 and D 90 , respectively.
• a measurement sample containing a solid electrolyte was prepared as follows.
• a measurement sample containing raw material powder was prepared as follows. First, as described later, a slurry containing raw material powder (raw material slurry) was prepared. Next, several drops of a dispersant (SN Dispersant 9228, manufactured by San Nopco Co., Ltd.) were added dropwise to the organic solvent (toluene), and then several drops of the slurry containing the raw material powder were added to prepare a measurement sample containing the raw material powder. .
• SN Dispersant 9228 manufactured by San Nopco Co., Ltd.
• the CS value of the powder is the surface area per unit volume of the powder, assuming that the shape of the particles constituting the powder is spherical, and the unit is m 2 /cm 3 .
• the particle size distribution was measured using a laser diffraction particle size distribution analyzer "MT3000II” manufactured by Microtrac Bell Co., Ltd. in the same manner as the measurement of D50 and D90 , and the obtained volume-based particle size distribution
• the CS value was calculated from the chart. (true density)
• the true density was calculated by the gas displacement method using a true density evaluation device "BELPycno” manufactured by Microtrac Bell Co., Ltd. Pretreatment was performed five times using purge. A 10 cc alumina cell was used for the measurement, and the sample was filled to about 70% of the cell.
• the unit of the true density determined in this manner is g/cm 3 .
• the value calculated based on the particle size distribution measurement is the surface area calculated by dividing the CS value (m 2 / cm 3 ), which is obtained assuming that the particles are spherical, by the true density (g / cm 3 ). This is defined as the specific surface area S2 (m 2 /g) calculated from the particle size distribution.
• the measurement conditions are as follows.
• ⁇ Optical system Concentrated beam method
• ⁇ Detector One-dimensional detector
• ⁇ Measurement well range: 2 ⁇ 10-120° ⁇ Step width: 0.02°
• ⁇ Scan speed 1°/min
• SRM660c compound name: LaB6 manufactured by NIST (National Institute of Standards and Technology) was measured under the same conditions and used as a width standard
• SRM640f compound name: Si was measured under the same conditions.
• This file corresponds to a file in which XRD data obtained by measuring SRM640f was identified with Si, analyzed using a method similar to the method shown below, and saved. Peak angles and widths were corrected using external standard samples. A "split type pseudo-Voigt function" was used as a model function for the peak shape. Next, from the "Basics” tab, “Refined parameter settings” - “Method” was selected and “Rietveld/dl pattern” was selected. Next, refinement was carried out. During refinement, various parameters were adjusted until sufficient convergence was achieved. For example, the standard S value is 1.5 or less. The analyzed crystallite size was obtained from "Display” - "Analysis results".
• ⁇ Ionic conductivity> The solid electrolyte powders obtained in Examples and Comparative Examples were uniaxially pressed under a load of approximately 6 t/cm 2 in a glove box purged with sufficiently dried Ar gas (dew point -60°C or less).
• a sample for measuring lithium ion conductivity was prepared by molding a pellet having a diameter of 10 mm and a thickness of about 1 mm to 8 mm. Measurements of lithium ion conductivity were performed using a Solartron 1255B electrochemical measurement system (1280C) and an impedance/gain phase analyzer (SI 1260) manufactured by Solartron Analytical. The measurement conditions were an AC impedance method with a temperature of 25° C., a frequency of 100 Hz to 1 MHz, and an amplitude of 100 mV.
• ⁇ Particle size change> When the pulverization step is performed only once, the difference between the particle size d B1 ( ⁇ m) of the unpulverized sulfur compound and the particle size d B2 ( ⁇ m) of the sulfur compound after the pulverization step (d B1 ⁇ d B2 ) ( ⁇ m ) was calculated.
• the particle size dB3 ( ⁇ m) of the sulfur compound before the arbitrary pulverization step and the particle size d of the sulfur compound immediately after the arbitrary pulverization step are performed.
• the difference ( d B3 - d B4 ) ( ⁇ m) from B4 ( ⁇ m) was calculated.
• Example 2 The bead diameter was 0.5 mm, the grinding time for main grinding was 35 minutes, and the ratio D2/D1 of the median diameter D1 of the solid electrolyte powder after preliminary grinding to the median diameter D2 of the solid electrolyte powder after main grinding was 0.
• a solid electrolyte powder was obtained in the same manner as in Example 1, except that the pulverization time per 1 g (t/m) was 2.3 min/g. The results are shown in Table 1.
• Example 1 The bead diameter was 0.3 mm, the main grinding time was 35 minutes, a 10°C refrigerant was flowed through the jacket of the bead mill, and the median diameter D1 of the solid electrolyte powder after preliminary grinding and the solid electrolyte powder after main grinding were determined.
• a solid electrolyte powder was obtained in the same manner as in Example 1, except that the ratio D2/D1 with the median diameter D2 was 0.49 and the crushing time (t/m) per 1 g was 2.3 min/g. . The results are shown in Table 1.
• the ionic conductivity (specifically Specifically, it can be seen that the value of ionic conductivity (S/cm) relative to volume cumulative particle size D 50 ( ⁇ m) (ion conductivity/D 50 ) is higher than 1.3 ⁇ 10 ⁇ 3 .
• (ionic conductivity/D 50 ) is 1.3 ⁇ 10 ⁇ 3 , and it can be seen that this value is lower than that of the example.
• solid electrolyte powder that constitutes a solid electrolyte with excellent ionic conductivity.

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