WO2024014418A1 - 硫化物固体電解質の製造方法 - Google Patents

硫化物固体電解質の製造方法 Download PDF

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WO2024014418A1
WO2024014418A1 PCT/JP2023/025368 JP2023025368W WO2024014418A1 WO 2024014418 A1 WO2024014418 A1 WO 2024014418A1 JP 2023025368 W JP2023025368 W JP 2023025368W WO 2024014418 A1 WO2024014418 A1 WO 2024014418A1
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Prior art keywords
solid electrolyte
complexing agent
sulfide solid
electrolyte
heated air
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English (en)
French (fr)
Japanese (ja)
Inventor
康人 籠田
裕一 笠谷
勇介 井関
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Idemitsu Kosan Co Ltd
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Idemitsu Kosan Co Ltd
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Priority to EP23839590.9A priority Critical patent/EP4557317A1/en
Priority to JP2024533696A priority patent/JPWO2024014418A1/ja
Priority to KR1020257000089A priority patent/KR20250037746A/ko
Priority to CN202380052014.5A priority patent/CN119497896A/zh
Priority to US18/992,216 priority patent/US20260008676A1/en
Publication of WO2024014418A1 publication Critical patent/WO2024014418A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/022—Electrolytes; Absorbents
    • H01G9/025—Solid electrolytes
    • 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
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/56—Solid electrolytes, e.g. gels; Additives therein
    • 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
    • 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
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • 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 producing a sulfide solid electrolyte.
  • Methods for manufacturing the solid electrolyte used in the solid electrolyte layer are broadly divided into solid phase method and liquid phase method.
  • a heterogeneous method in which the material is not completely dissolved, but instead undergoes a suspension in which solid and liquid coexist.
  • a method in which a solid electrolyte is dissolved in a solvent and reprecipitated is known as a homogeneous method (see, for example, Patent Document 1)
  • a method in which a polar aprotic solvent is used is known.
  • a method is known in which a solid electrolyte raw material such as lithium sulfide is reacted in a solvent containing lithium sulfide (see, for example, Patent Documents 2 and 3 and Non-Patent Document 1).
  • a method for manufacturing a solid electrolyte includes using a specific compound having an amino group as a complexing agent and mixing the complexing agent and a solid electrolyte raw material to prepare an electrolyte precursor (for example, see Patent Document 4). ), and a method for producing a solid electrolyte that includes drying a slurry containing a complexing agent and an electrolyte precursor by fluidized drying using media particles (see, for example, Patent Document 5).
  • the present invention has been made in view of these circumstances, and provides a manufacturing method that efficiently manufactures a sulfide solid electrolyte having high ionic conductivity while employing a liquid phase method, and that can be easily mass-produced.
  • the purpose is to provide
  • the method for producing a sulfide solid electrolyte according to the present invention includes: Mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom with a complexing agent to obtain an electrolyte precursor containing material; then heating in a heated air stream; A method for producing a sulfide solid electrolyte, It is.
  • the present invention it is possible to provide a manufacturing method that efficiently manufactures a sulfide solid electrolyte having high ionic conductivity while employing a liquid phase method, and that can be easily mass-produced.
  • FIG. 2 is a flow diagram of an apparatus including a flash dryer and a bag filter used in Example 1.
  • 3 is an X-ray diffraction spectrum of the crystalline sulfide solid electrolyte obtained in Example 3. This is an X-ray diffraction spectrum of the crystalline sulfide solid electrolytes obtained in Examples 3 to 8.
  • 1 is an X-ray diffraction spectrum of crystalline sulfide solid electrolytes obtained in Comparative Examples 1 and 2.
  • FIG. 3 is a flow diagram of an apparatus including a fluidized bed dryer and a bag filter used in Comparative Example 3.
  • 3 is an X-ray diffraction spectrum of the crystalline sulfide solid electrolytes obtained in Comparative Example 3 and Examples 3 and 6. This is an X-ray diffraction spectrum of the crystalline sulfide solid electrolytes obtained in Examples 9 to 15.
  • this embodiment an embodiment of the present invention (hereinafter sometimes referred to as “this embodiment") will be described.
  • the upper and lower limits of numerical ranges of "more than”, “less than”, and “ ⁇ ” can be arbitrarily combined, and the numerical values of Examples are used as the upper and lower limits. You can also do that.
  • regulations considered to be preferable can be arbitrarily adopted. That is, one regulation considered to be preferable can be employed in combination with one or more other regulations considered to be preferable. It can be said that a combination of preferable items is more preferable.
  • the liquid-phase method has been attracting attention as a method that not only has versatility and applicability, but also is simple and can be synthesized in large quantities.
  • the liquid phase method has higher ionic conductivity than the solid phase method because the solid electrolyte is dissolved, so some of the solid electrolyte components may be decomposed or damaged during precipitation. There is a problem that it is difficult to realize the degree. For example, in the homogeneous method, the raw materials and solid electrolyte are once completely dissolved, so that the components can be uniformly dispersed in the liquid.
  • the step of removing the complexing agent is It becomes necessary.
  • the present inventors focused on a method of removing a complexing agent in a method of producing a sulfide solid electrolyte through an electrolyte precursor using a complexing agent.
  • the complexing agent is removed by drying the slurry-like electrolyte precursor-containing material under vacuum and at room temperature to form a powder electrolyte precursor, and then drying the electrolyte precursor under vacuum. This is carried out by heating at 120° C. (Example 1, etc.), and specifically, by using a jacket type heater (such as a vibration dryer) under vacuum. In this way, when a complexing agent is used, the complexing agent cannot be removed from the electrolyte precursor by mere drying, and heating must be performed using a jacket-type heater (such as a vibration dryer). .
  • the complexing agent can be removed, the localized high temperature on the inner wall of the heater causes agglomeration of the halogen compounds contained in the solid electrolyte, causing deterioration of the solid electrolyte. There was a case. Therefore, there are restrictions on the temperature conditions when removing the complexing agent, and there is room for improvement in terms of efficiently producing a solid electrolyte. Furthermore, with the increasing demand for sulfide solid electrolytes, there is a need for mass production. However, in the conventional method, the complexing agent is removed in an environment where heat is only transferred by the powder coming into contact with the inner wall (heat transfer surface) of a jacket-type heater because heating is performed under vacuum. As a result, there was a concern that this would have a large impact on the size of the equipment, and that it would not be possible to respond adequately.
  • the present inventors investigated a method for removing a complexing agent from an electrolyte precursor formed from a complexing agent and a solid electrolyte raw material, and found that an electrolyte precursor-containing material was supplied into a heated air stream. It has been found that the complexing agent can be removed from the electrolyte precursor contained in the electrolyte precursor-containing material. If the complexing agent is removed from the electrolyte precursor by heating in a heated air stream, the solid electrolyte is formed by contact between the solid electrolyte powder and the locally hot wall of a jacket-type heater (such as a vibration dryer). It is possible to suppress the deterioration of
  • the method for producing a sulfide solid electrolyte according to the first form of the present embodiment includes: Mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom with a complexing agent to obtain an electrolyte precursor containing material; then heating in a heated air stream; A method for producing a sulfide solid electrolyte, It is.
  • the electrolyte precursor-containing substance obtained by mixing the solid electrolyte raw material and the complexing agent does not contribute to the formation of the electrolyte precursor together with the electrolyte precursor.
  • Complexing agents and solid electrolyte raw materials as well as solvents may be included.
  • the complexing agent can be removed from the electrolyte precursor by heating in a heated air stream. In addition, if a remaining complexing agent or solvent that does not contribute to the formation of the electrolyte precursor is included, these can also be removed.
  • the electrolyte precursor is a precursor of the sulfide solid electrolyte obtained by the manufacturing method of this embodiment, and can become a sulfide solid electrolyte by removing the complexing agent.
  • the complexing agent refers to a complexing agent, that is, an agent capable of forming a complex, and refers to a compound that is likely to form a complex with the solid electrolyte raw material contained in the raw material containing material. Therefore, since the electrolyte precursor is obtained by mixing the raw material containing material and the complexing agent, more specifically, it can be said that it is a complex formed by the solid electrolyte raw material via the complexing agent. .
  • the manufacturing method of the present embodiment includes obtaining the electrolyte precursor-containing material and then heating it in a heated air stream. Heating may be performed after obtaining the electrolyte precursor-containing material, and the heating target in the heating is the electrolyte precursor-containing material, and when drying, which will be described later, is performed, the electrolyte precursor-containing material is heated.
  • the electrolyte precursor-containing material and the electrolyte precursor may be collectively referred to as the "heating object".
  • the electrolyte precursor content particularly the electrolyte precursor contained in the electrolyte precursor content, may be heated in a heated air stream. It is essential.
  • the heated airflow has the functions of drying by temperature (heat) and airflow, dispersing the heated object and removing the complexing agent by the airflow, and these functions allow the complexing agent to be efficiently removed from the electrolyte precursor. It is thought that it can be removed. Since the object to be heated, such as the electrolyte precursor-containing material, comes into direct contact with the heated airflow and is dispersed in the heated airflow, the contact area between the electrolyte precursor and the heated airflow becomes large. Therefore, the complexing agent contained in the electrolyte precursor can be efficiently heated. Furthermore, the heated air stream allows the complexing agent to separate and be removed quickly.
  • regeneration of the complex regeneration of a complex between the electrolyte precursor from which the complexing agent has been removed and the complexing agent (hereinafter also simply referred to as “regeneration of the complex"), and impurities caused by the electrolyte precursor and the complexing agent. (hereinafter also simply referred to as “impurity generation”) is suppressed, so a sulfide solid electrolyte with few impurities, high quality, and high ionic conductivity can be obtained.
  • the method for producing a sulfide solid electrolyte according to the second aspect of the present embodiment includes, in the first aspect, drying the electrolyte precursor-containing material; That is what it is.
  • the electrolyte precursor-containing material is dried to remove the remaining complexing agent that does not contribute to the formation of the electrolyte precursor and the solvent used as necessary, and to remove the electrolyte precursor.
  • the body can be isolated as a powder and heated in a heated air stream.
  • drying in the manufacturing method of this embodiment removes the remaining complexing agent that does not contribute to the formation of the electrolyte precursor and the solvent used as necessary from the electrolyte precursor-containing material.
  • This is the main purpose. Therefore, the removal of the complexing agent from the electrolyte precursor is not performed by drying, but only by heating in a heated air stream.
  • the remaining complexing agent optionally the solvent, can be removed by heating in a heated air stream. Further, it goes without saying that the complexing agent can be removed from the electrolyte precursor by heating the electrolyte precursor-containing material in a heated air stream.
  • the method for producing a sulfide solid electrolyte according to the third aspect of the present embodiment includes, in the first or second aspect,
  • the temperature of the heated air flow is 100°C or more and 180°C or less, That is what it is.
  • the complexing agent contained in the electrolyte precursor is easily separated from the electrolyte precursor and removed due to the temperature (heat) of the heated airflow and the action of the airflow.
  • the temperature of the heated air stream within the above temperature range, heating due to the action of the temperature (heat) of the heated air stream is particularly promoted, so that the complexing agent is easily separated from the electrolyte precursor and removed.
  • the separated gaseous complexing agent is easily discharged out of the system along with the heated airflow, the regeneration of the complex and the generation of impurities by the separated complexing agent are suppressed, resulting in fewer impurities and improved quality. This makes it easier to obtain a sulfide solid electrolyte with high ionic conductivity.
  • a method for producing a sulfide solid electrolyte according to a fourth aspect of the present embodiment includes, in the first to third aspects, The supply amount of the heated air flow is 0.1 m 3 /min or more and 500 m 3 /min or less, That is what it is.
  • the heating object can be more efficiently dispersed and the complexing agent can be separated and removed due to the action of the heated airflow. Therefore, the regeneration of the complex and the generation of impurities are suppressed, making it easier to obtain a sulfide solid electrolyte with less impurities, high quality, and high ionic conductivity more efficiently. Further, by suppressing the supply amount of the heated air flow within a certain range, it becomes possible to more easily respond to mass production.
  • the method for producing a sulfide solid electrolyte according to the fifth aspect of the present embodiment includes the steps of the first to fourth aspects described above.
  • the flow velocity of the heated air current is 5 m/s or more and 35 m/s or less, That is what it is.
  • the complexing agent contained in the electrolyte precursor is easily separated from the electrolyte precursor and removed due to the temperature (heat) of the heated airflow and the action of the airflow.
  • the flow rate of the heated air stream within the above temperature range, separation and removal of the complexing agent by the action of the heated air stream can be promoted more efficiently. Since the separated gaseous complexing agent is easily discharged out of the system along with the heated airflow, the regeneration of the complex and the generation of impurities by the separated complexing agent are suppressed, resulting in less impurities and improved quality. This makes it easier to obtain a sulfide solid electrolyte with high ionic conductivity.
  • the method for producing a sulfide solid electrolyte according to the sixth aspect of the present embodiment includes, in the first to fifth aspects, Heating in the heated air stream is performed for 0.1 seconds or more and 1 minute or less, That is what it is.
  • the complexing agent contained in the electrolyte precursor can be efficiently removed by heating using a heated air flow. Therefore, heating by the heated airflow can be performed in a short time of 0.1 seconds or more and 1 minute or less.
  • the method for producing a sulfide solid electrolyte according to the seventh aspect of the present embodiment includes, in the second to sixth aspects, The drying is carried out at a temperature of 5° C. or higher and 110° C. or lower under normal pressure or reduced pressure. That is what it is.
  • the pressure condition is from normal pressure to reduced pressure, and the temperature condition is 5°C or more and 110°C or less, so that the electrolyte precursor-containing material can be dried more efficiently and the electrolyte A precursor is obtained.
  • the method for producing a sulfide solid electrolyte according to the eighth aspect of the present embodiment includes, in the second to seventh aspects, further heating after heating in the heated air stream; That is what it is.
  • the complexing agent is removed from the electrolyte precursor, and an amorphous sulfide solid electrolyte is obtained.
  • an amorphous sulfide solid electrolyte is obtained.
  • a crystalline sulfide solid electrolyte can be obtained.
  • a method for producing a sulfide solid electrolyte according to a ninth aspect of the present embodiment includes, in the first to eighth aspects, the complexing agent is a compound having an amino group; In addition, the method for producing a sulfide solid electrolyte according to the tenth aspect of the present embodiment includes, in the first to ninth aspects, the complexing agent is a compound having at least two tertiary amino groups in the molecule; That is what it is.
  • the complexing agent is a solvent that has the property of forming a complex with the solid electrolyte raw material contained in the raw material content, as described above.
  • a compound having a hetero atom tends to have the property of forming a complex with the solid electrolyte raw material, and is therefore a preferable compound as a complexing agent.
  • compounds that have a nitrogen atom as a heteroatom and a nitrogen atom as an amino group not only make it easier to form a complex, but also make it easier to incorporate halogen atoms, which are difficult to incorporate into complex formation, and make solid electrolyte raw materials This makes it easier to maintain a uniform dispersion state. Therefore, it becomes easier to obtain higher ionic conductivity.
  • a compound having an amino group when used as a complexing agent, in addition to the above properties, it also has the property of being easy to separate from the electrolyte precursor and easy to remove. Therefore, the regeneration of the complex and the generation of impurities are suppressed, and a sulfide solid electrolyte with few impurities, high quality, and high ionic conductivity can be obtained very efficiently.
  • the method for producing a sulfide solid electrolyte according to the eleventh aspect of the present embodiment includes, in the first to tenth aspects, In heating in the heated air stream, no media particles are used; That is what it is.
  • the manufacturing method of this embodiment it is important to heat the electrolyte precursor in a heated air stream, and it is preferable not to use media particles. It is possible to suppress excessive contact with the heated air flow due to the adhesion of the electrolyte precursor to the media particles, and it is possible to suppress the deterioration of the amorphous sulfide solid electrolyte due to deterioration of the electrolyte precursor, resulting in high ionic conductivity.
  • heating in a heated air stream only means heating with a heated air stream, and thereby the complexing agent can be efficiently removed from the electrolyte precursor, resulting in a high It becomes possible to efficiently produce a sulfide solid electrolyte having ionic conductivity.
  • the method for producing a sulfide solid electrolyte according to the twelfth aspect of the present embodiment includes, in the first to eleventh aspects,
  • the sulfide solid electrolyte has a thiolisicone region II type crystal structure, That is what it is.
  • a sulfide solid electrolyte having a thiolithicone region type II crystal structure is known as a sulfide solid electrolyte with extremely high ionic conductivity, and is preferable as the sulfide solid electrolyte to be obtained by the manufacturing method of the present embodiment. be.
  • solid electrolyte means an electrolyte that remains solid at 25° C. under a nitrogen atmosphere.
  • the solid electrolyte in this embodiment includes a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, and has ionic conductivity due to the lithium atom.
  • Solid electrolyte includes both amorphous solid electrolytes and crystalline solid electrolytes.
  • a crystalline solid electrolyte is a solid electrolyte in which a peak derived from the solid electrolyte is observed in an X-ray diffraction pattern in an X-ray diffraction measurement, and whether or not there is a peak derived from the raw material of the solid electrolyte. is not a question. That is, a crystalline solid electrolyte includes a crystal structure derived from a solid electrolyte, and even if part of the crystal structure is derived from the solid electrolyte, or the entire crystal structure is derived from the solid electrolyte. good.
  • the crystalline solid electrolyte has an X-ray diffraction pattern as described above, a part of the crystalline solid electrolyte may include an amorphous solid electrolyte. Therefore, the crystalline solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte to a temperature higher than the crystallization temperature.
  • an amorphous solid electrolyte is one that has a halo pattern in which no peaks other than peaks derived from the material are substantially observed in the X-ray diffraction pattern in X-ray diffraction measurement; It does not matter whether or not there is a peak derived from the raw material.
  • the method for manufacturing the sulfide solid electrolyte of this embodiment is as follows: Mixing a raw material containing a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom with a complexing agent to obtain an electrolyte precursor containing material; then heating in a heated air stream; A method for producing a sulfide solid electrolyte, It is.
  • the manufacturing method of this embodiment includes mixing a raw material containing material containing a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom with a complexing agent to obtain an electrolyte precursor containing material.
  • the manufacturing method of this embodiment will be explained first starting from the raw material content.
  • the raw material containing material used in this embodiment contains a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, and more specifically, a compound containing one or more types selected from the group consisting of these atoms (hereinafter referred to as (also referred to as "solid electrolyte raw material").
  • the raw material-containing material used in this embodiment preferably contains two or more types of solid electrolyte raw materials.
  • Examples of solid electrolyte raw materials included in the raw material include lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; diphosphorus trisulfide (P 2 S 3 ), diphosphorus pentasulfide, Phosphorus sulfide such as phosphorus (P 2 S 5 ); various phosphorus fluorides (PF 3 , PF 5 ), various phosphorus chlorides (PCl 3 , PCl 5 , P 2 Cl 4 ), various phosphorus bromides (PBr 3 , PBr 5 ) ), phosphorus halides such as various phosphorus iodides (PI 3 , P 2 I 4 ); thiophosphoryl fluoride (PSF 3 ), thiophosphoryl chloride (PSCl 3 ), thiophosphoryl bromide (PSBr 3 ), thioiodide At least two types selected from the above four types of atoms, such as
  • Examples of materials that can be used as solid electrolyte raw materials other than those mentioned above include, for example, solid electrolyte raw materials that contain at least one type of atom selected from the above four types of atoms and that also contain atoms other than the four types of atoms; , lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS) 2 ) Metal sulfides such as aluminum sulfide and zinc sulfide; phosphoric acid compounds such as sodium phosphate and lithium phosphate; non-lithium halides such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; Al
  • lithium sulfide phosphorus sulfide such as diphosphorus trisulfide (P 2 S 3 ), diphosphorus pentasulfide (P 2 S 5 ), fluorine (F 2 ), chlorine (Cl 2 ), bromine (Br 2 ) , iodine (I 2 ), and lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide are preferable.
  • phosphoric acid compounds such as lithium oxide, lithium hydroxide, and lithium phosphate are preferred.
  • Preferred combinations of solid electrolyte raw materials include, for example, a combination of lithium sulfide, diphosphorus pentasulfide, and lithium halide, and a combination of lithium sulfide, diphosphorus pentasulfide, and a simple halogen;
  • examples of the lithium halide include lithium bromide, Lithium iodide is preferred, and as the halogen element, bromine and iodine are preferred.
  • Li 3 PS 4 containing a PS 4 structure can also be used as part of the raw material.
  • Li 3 PS 4 is prepared by first producing it, and this is used as a raw material.
  • the content of Li 3 PS 4 relative to the total raw materials is preferably 60 to 100 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 80 mol%.
  • the content of the simple halogen with respect to Li 3 PS 4 is preferably 1 to 50 mol%, more preferably 10 to 40 mol%, even more preferably 20 to 30 mol%, and 22 -28 mol% is even more preferred.
  • the lithium sulfide used in this embodiment is preferably in the form of particles.
  • the average particle diameter (D 50 ) of the lithium sulfide particles is preferably 0.1 ⁇ m or more and 1000 ⁇ m or less, more preferably 0.5 ⁇ m or more and 100 ⁇ m or less, and even more preferably 1 ⁇ m or more and 20 ⁇ m or less.
  • the average particle diameter (D 50 ) is the particle diameter at which 50% (by volume) of the total particle size is reached when a particle size distribution integration curve is drawn and the particle diameter is accumulated sequentially starting from the smallest particle size.
  • the volume distribution is an average particle size that can be measured using, for example, a laser diffraction/scattering particle size distribution measuring device.
  • the solid raw materials listed as the raw materials above it is preferable that the solid raw materials have the same average particle size as the lithium sulfide particles, that is, those within the same range as the average particle size of the lithium sulfide particles. preferable.
  • the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide can obtain higher chemical stability and higher ionic conductivity. From this point of view, it is preferably 65 to 85 mol%, more preferably 70 to 82 mol%, and even more preferably 74 to 80 mol%.
  • the content of lithium sulfide and diphosphorus pentasulfide relative to the total of these is preferably 50 to 99 mol%, More preferably 55 to 85 mol%, and even more preferably 60 to 80 mol%.
  • the ratio of lithium bromide to the total of lithium bromide and lithium iodide should be 1 to 99 mol from the viewpoint of improving ionic conductivity. %, more preferably 20 to 80 mol%, even more preferably 35 to 80 mol%, particularly preferably 45 to 70 mol%. Furthermore, when using a combination of lithium bromide and lithium chloride as lithium halides, the proportion of lithium bromide to the total of lithium bromide and lithium chloride should be 1 to 99 mol% from the viewpoint of improving ionic conductivity. It is preferably 15 to 75 mol%, even more preferably 25 to 60 mol%, and particularly preferably 35 to 45 mol%.
  • the total number of moles of lithium sulfide and diphosphorus pentasulfide excluding the same number of moles of lithium sulfide as the number of moles of the elemental halogen.
  • the ratio of the number of moles of lithium sulfide, excluding the number of moles of halogen alone and the same number of moles of lithium sulfide, is preferably within the range of 60 to 90%, and preferably within the range of 65 to 85%.
  • the content of the elemental halogen with respect to the total amount of lithium sulfide, diphosphorus pentasulfide, and elemental halogen is 1 to 50 mol%. is preferable, 2 to 40 mol% is more preferable, 3 to 25 mol% is even more preferable, and 3 to 15 mol% is even more preferable.
  • the content of elemental halogen ( ⁇ mol%) and the content of lithium halide ( ⁇ mol%) with respect to the total amount are as follows. It is preferable to satisfy formula (2), more preferably to satisfy formula (3) below, even more preferably to satisfy formula (4) below, and even more preferably to satisfy formula (5) below. 2 ⁇ 2 ⁇ + ⁇ 100...(2) 4 ⁇ 2 ⁇ + ⁇ 80...(3) 6 ⁇ 2 ⁇ + ⁇ 50...(4) 6 ⁇ 2 ⁇ + ⁇ 30...(5)
  • A1 is the number of moles of one halogen atom in the substance
  • A2 is the number of moles of the other halogen atom in the substance
  • A1:A2 is 1 to 99:
  • the ratio is preferably 99-1, more preferably 10:90-90:10, even more preferably 20:80-80:20, even more preferably 30:70-70:30.
  • A1:A2 is 1:99 ⁇
  • the ratio is preferably 99:1, more preferably 20:80 to 80:20, even more preferably 35:65 to 80:20, and even more preferably 45:55 to 70:30.
  • B1:B2 is preferably 1:99 to 99:1, and 15:85. 75:25 is more preferable, 25:75 to 60:40 is even more preferable, and 35:45 to 65:55 is even more preferable.
  • the complexing agent is a compound that easily forms a complex with the solid electrolyte raw material contained in the raw material content, for example, lithium sulfide and diphosphorus pentasulfide, which are preferably used as solid electrolyte raw materials, It is a compound that can form a complex with Li 3 PS 4 obtained when the solid electrolyte raw material is used, and also with a solid electrolyte raw material containing a halogen atom (hereinafter also collectively referred to as "solid electrolyte raw material etc.”).
  • any compound having the above-mentioned properties can be used without particular restriction, and in particular, compounds containing atoms with high affinity for lithium atoms, such as heteroatoms such as nitrogen atoms, oxygen atoms, and chlorine atoms. are preferred, and compounds having a group containing these heteroatoms are more preferred. This is because these heteroatoms and groups containing the heteroatoms can coordinate (bond) with lithium.
  • the heteroatoms present in the molecules of the complexing agent have a high affinity with lithium atoms, and have the property of easily bonding with solid electrolyte raw materials to form a complex (hereinafter also simply referred to as "complex"). It is considered to be. Therefore, by mixing the solid electrolyte raw material and the complexing agent, a complex is formed, and the dispersion state of the solid electrolyte raw material, especially the dispersion state of the halogen atoms, is easily maintained uniformly, and as a result, the ionic conductivity is increased. It is thought that a high sulfide solid electrolyte can be obtained.
  • the ability of the complexing agent to form a complex with the solid electrolyte raw material and the like can be directly confirmed, for example, by an infrared absorption spectrum measured by FT-IR analysis (diffuse reflection method).
  • FT-IR analysis a powder obtained by stirring tetramethylethylenediamine (hereinafter also simply referred to as "TMEDA"), which is one of the preferable complexing agents, and lithium iodide (LiI), and the complexing agent itself.
  • TMEDA tetramethylethylenediamine
  • LiI lithium iodide
  • LiI-TMEDA complex is formed by stirring and mixing TMEDA and lithium iodide (for example, see Aust. J. Chem., 1988, 41, 1925-34, especially Fig. 2) etc., it is reasonable to assume that a LiI-TMEDA complex is formed.
  • a powder obtained by stirring a complexing agent (TMEDA) and Li 3 PS 4 is analyzed by FT-IR analysis (diffuse reflection method) in the same manner as above, the spectrum of TMEDA itself is , 1000 to 1250 cm ⁇ 1 , it can be confirmed that the peaks derived from the CN stretching vibration are different, but it can also be confirmed that the spectrum is similar to that of the LiI-TMEDA complex. From this, it may be considered that a Li 3 PS 4 -TMEDA complex is formed.
  • a complex obtained by mixing a raw material containing material and a complexing agent is used as an electrolyte precursor, and the complexing agent is removed from the electrolyte precursor powder in a heated air flow. In this way, a sulfide solid electrolyte is produced.
  • the complexing agent preferably has at least two coordinating (bondable) heteroatoms in the molecule, and more preferably has a group containing at least two heteroatoms in the molecule.
  • a group containing at least two heteroatoms in the molecule solid electrolyte raw materials, etc. can be bonded via at least two heteroatoms in the molecule.
  • a nitrogen atom is preferable, and as a group containing a nitrogen atom, an amino group is preferable. That is, an amine compound is preferable as the complexing agent.
  • the amine compound is not particularly limited as long as it has an amino group in its molecule since it can promote the formation of a complex, but a compound having at least two amino groups in its molecule is preferred. With such a structure, solid electrolyte raw materials and the like can be bonded via at least two nitrogen atoms in the molecule to form a complex.
  • amine compounds examples include amine compounds such as aliphatic amines, alicyclic amines, heterocyclic amines, and aromatic amines, which can be used alone or in combination.
  • aliphatic amines include aliphatic primary diamines such as ethylenediamine, diaminopropane, and diaminobutane; N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, and N,N'-dimethyldiaminopropane.
  • N,N'-diethyldiaminopropane N,N,N',N'-tetramethyldiaminomethane, N,N,N',N'-tetramethylethylenediamine, N,N, N',N'-tetraethylethylenediamine, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraethyldiaminopropane, N,N,N',N'-tetramethyl Aliphatic diamines such as diaminobutane, N,N,N',N'-tetramethyldiaminopentane, N,N,N',N'-tetramethyldiaminohexane; and the like are typically preferred.
  • the number of carbon atoms in the aliphatic amine is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and still more preferably 7 or less.
  • the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic amine is preferably 2 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.
  • alicyclic amines examples include alicyclic primary diamines such as cyclopropanediamine and cyclohexane diamine; alicyclic secondary diamines such as bisaminomethylcyclohexane; N,N,N',N'-tetramethyl-cyclohexane diamine, Alicyclic tertiary diamines such as bis(ethylmethylamino)cyclohexane; representative examples of preferred examples include alicyclic diamines; examples of heterocyclic amines include primary heterocyclic diamines such as isophorone diamine; and piperazine.
  • heterocyclic secondary diamines such as dipiperidylpropane
  • heterocyclic tertiary diamines such as N,N-dimethylpiperazine and bismethylpiperidylpropane.
  • the number of carbon atoms in the alicyclic amine and heterocyclic amine is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.
  • aromatic amines include aromatic primary diamines such as phenyldiamine, tolylenediamine, and naphthalenediamine; N-methylphenylenediamine, N,N'-dimethylphenylenediamine, N,N'-bismethylphenylphenylenediamine, Aromatic secondary diamines such as N,N'-dimethylnaphthalenediamine and N-naphthylethylenediamine; N,N-dimethylphenylenediamine, N,N,N',N'-tetramethylphenylenediamine, N,N,N' , N'-tetramethyldiaminodiphenylmethane, and aromatic tertiary diamines such as N,N,N',N'-tetramethylnaphthalene diamine.
  • the number of carbon atoms in the aromatic amine is preferably 6 or more, more preferably 7 or more, still more preferably 8 or more, and the upper limit is
  • the amine compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom.
  • a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom.
  • diamine is given as a specific example, it goes without saying that the amine compound that can be used in this embodiment is not limited to diamine, and includes various diamines such as trimethylamine, triethylamine, ethyldimethylamine, and the above-mentioned aliphatic diamines.
  • monoamines such as alicyclic monoamines such as monoamines corresponding to the above-mentioned alicyclic diamines, heterocyclic monoamines corresponding to the above-mentioned heterocyclic diamines, and aromatic monoamines corresponding to the above-mentioned aromatic diamines, for example, diethylenetriamine, N ,N',N'-trimethyldiethylenetriamine, N,N,N',N'',N'-pentamethyldiethylenetriamine, triethylenetetramine, N,N'-bis[(dimethylamino)ethyl
  • a tertiary amine having a tertiary amino group as an amino group is preferable, and a tertiary diamine having two tertiary amino groups is more preferable.
  • a tertiary diamine having two tertiary amino groups at both ends is more preferred, and an aliphatic tertiary diamine having tertiary amino groups at both ends is even more preferred.
  • tetramethylethylenediamine, tetraethylethylenediamine, tetramethyldiaminopropane, and tetraethyldiaminopropane are preferable, and considering ease of acquisition, etc. Tetramethylethylenediamine and tetramethyldiaminopropane are preferred.
  • the complexing agent is preferably a compound containing an oxygen atom as well as a compound containing the above-mentioned nitrogen atom as a hetero atom.
  • a compound containing an oxygen atom a compound having one or more functional groups selected from an ether group and an ester group as a group containing an oxygen atom is preferable, and among these, a compound having an ether group is particularly preferable. That is, as the complexing agent containing an oxygen atom, an ether compound is particularly preferable.
  • ether compound examples include ether compounds such as aliphatic ether, alicyclic ether, heterocyclic ether, and aromatic ether, which can be used alone or in combination.
  • the aliphatic ethers include monoethers such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tert-butyl methyl ether; diethers such as dimethoxymethane, dimethoxyethane, diethoxymethane, and diethoxyethane; Examples include polyethers having three or more ether groups such as diethylene glycol dimethyl ether (diglyme) and triethylene oxide glycol dimethyl ether (triglyme); and ethers containing hydroxyl groups such as diethylene glycol and triethylene glycol.
  • monoethers such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tert-butyl methyl ether
  • diethers such as dimethoxymethane, dimethoxyethane, diethoxymethane, and diethoxyethane
  • Examples include polyethers having three or more ether groups
  • the number of carbon atoms in the aliphatic ether is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.
  • the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ether is preferably 1 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less.
  • alicyclic ethers examples include ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, dioxane, and dioxolane
  • heterocyclic ethers include furan, benzofuran, benzopyran, dioxene, and dioxin. , morpholine, methoxyindole, hydroxymethyldimethoxypyridine and the like.
  • the number of carbon atoms in the alicyclic ether and heterocyclic ether is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.
  • aromatic ethers examples include methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, diphenyl ether, benzylphenyl ether, and naphthyl ether.
  • the number of carbon atoms in the aromatic ether is preferably 7 or more, more preferably 8 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, still more preferably 12 or less.
  • the ether compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom.
  • aliphatic ethers are preferred, and dimethoxyethane and tetrahydrofuran are more preferred, from the viewpoint of obtaining higher ionic conductivity.
  • ester compound examples include ester compounds such as aliphatic esters, alicyclic esters, heterocyclic esters, and aromatic esters, which can be used alone or in combination.
  • aliphatic esters include formic esters such as methyl formate, ethyl formate, and triethyl formate; acetate esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; methyl propionate; , propionic acid esters such as ethyl propionate, propyl propionate, and butyl propionate; oxalic acid esters such as dimethyl oxalate and diethyl oxalate; malonic acid esters such as dimethyl malonate and diethyl malonate; dimethyl succinate, succinic acid Examples include succinate esters such as diethyl.
  • the number of carbon atoms in the aliphatic ester is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 7 or less. Further, the number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic ester is preferably 1 or more, more preferably 2 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, and still more preferably 3 or less. .
  • alicyclic esters examples include methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, dimethyl cyclohexanedicarboxylate, dibutyl cyclohexanedicarboxylate, dibutyl cyclohexenedicarboxylate, and examples of heterocyclic esters include methyl pyridinecarboxylate and pyridine. Examples include ethyl carboxylate, propyl pyridine carboxylate, methyl pyrimidine carboxylate, ethyl pyrimidine carboxylate, and lactones such as acetolactone, propiolactone, butyrolactone, and valerolactone.
  • the number of carbon atoms in the alicyclic ester and heterocyclic ester is preferably 3 or more, more preferably 4 or more, and the upper limit is preferably 16 or less, more preferably 14 or less.
  • aromatic esters examples include benzoic acid esters such as methyl benzoate, ethyl benzoate, propyl benzoate, and butyl benzoate; phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and dicyclohexyl phthalate; Examples include trimellitate esters such as mellitate, triethyl trimellitate, tripropyl trimellitate, tributyl trimellitate, and trioctyl trimellitate.
  • the number of carbon atoms in the aromatic ester is preferably 8 or more, more preferably 9 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less.
  • the ester compound used in this embodiment may be substituted with a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom.
  • a substituent such as an alkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, or a halogen atom.
  • ester compounds aliphatic esters are preferred, acetic esters are more preferred, and ethyl acetate is particularly preferred, from the viewpoint of obtaining higher ionic conductivity.
  • the amount of the complexing agent added is such that the molar ratio of the amount of the complexing agent added to the total molar amount of lithium atoms contained in the raw material is preferably 0.1 or more. .0 or less, more preferably 0.5 or more and 1.5 or less, still more preferably 0.8 or more and 1.2 or less, and most preferably 1.0.
  • the solid electrolyte raw material described above and a complexing agent are mixed.
  • the solid electrolyte raw material and the complexing agent may be mixed in either solid or liquid form, but since the solid electrolyte raw material contains solid and the complexing agent is liquid, it is usually A solid electrolyte material is mixed in a liquid complexing agent.
  • a solvent may be further mixed as necessary.
  • the complexing agent includes a solvent used as necessary.
  • the solid electrolyte raw material and the complexing agent may be mixed by charging the solid electrolyte raw material and the complexing agent into an apparatus capable of mixing the solid electrolyte raw material and the complexing agent.
  • an apparatus capable of mixing the solid electrolyte raw material and the complexing agent For example, if the solid electrolyte raw material is gradually added after the complexing agent is supplied into the tank and the stirring blade is activated, a good mixing state of the solid electrolyte raw material can be obtained and the dispersibility of the raw material will be improved. Therefore, it is preferable.
  • the solid electrolyte raw material may not be solid.
  • the solid electrolyte raw material is a liquid, it is sufficient to supply the complexing agent into the tank separately from other solid solid electrolyte raw materials, and if the solid electrolyte raw material is a gas, the complexing agent may be supplied into the tank separately.
  • the solid electrolyte raw material may be added to the solid electrolyte raw material.
  • the manufacturing method of this embodiment is characterized by including mixing a solid electrolyte raw material and a complexing agent.
  • a media-type pulverizer such as a ball mill or bead mill, which is generally called a pulverizer, for the purpose of pulverizing the solid electrolyte raw material. It can also be manufactured by a method that does not use the equipment used.
  • the solid electrolyte raw material and the complexing agent contained in the raw material content are mixed, and a complex, that is, an electrolyte precursor is formed. obtain.
  • the mixture of the raw material and the complexing agent may be ground with a grinder, but as mentioned above, a grinder is not used. It is preferable.
  • the electrolyte precursor may be ground by a grinder.
  • Examples of the device for mixing the solid electrolyte raw material and the complexing agent include a mechanical stirring mixer equipped with stirring blades in a tank.
  • Mechanical stirring mixers include high-speed stirring mixers, double-arm mixers, etc., which improve the uniformity of the solid electrolyte raw material in the mixture of the solid electrolyte raw material and the complexing agent, and achieve higher ionic conductivity. From the viewpoint of obtaining the desired amount, a high-speed stirring type mixer is preferably used. Further, examples of the high-speed stirring type mixer include a vertical axis rotation type mixer and a horizontal axis rotation type mixer, and either type of mixer may be used.
  • the shapes of stirring blades used in mechanical stirring mixers include anchor type, blade type, arm type, ribbon type, multi-stage blade type, double arm type, shovel type, twin-shaft blade type, flat blade type, and C type.
  • a shovel type, a flat blade type, a C-type blade type, etc. are preferable from the viewpoint of improving the uniformity of the solid electrolyte raw material and obtaining higher ionic conductivity.
  • the installation location of the circulation line is not particularly limited, but it is preferably installed at a location where the circulation line is discharged from the bottom of the mixer and returned to the top of the mixer. This makes it easier to uniformly stir the solid electrolyte raw material, which tends to settle, by placing it on the convection caused by circulation. Furthermore, it is preferable that the return port is located below the surface of the liquid to be stirred. By doing so, it is possible to suppress the liquid to be stirred from splashing and adhering to the wall surface inside the mixer.
  • the temperature conditions for mixing the solid electrolyte raw material and the complexing agent are not particularly limited, and are, for example, -30 to 100°C, preferably -10 to 50°C, more preferably around room temperature (23°C) (for example, room temperature (approximately ⁇ 5°C).
  • the mixing time is about 0.1 to 150 hours, preferably 1 to 120 hours, more preferably 4 to 100 hours, even more preferably 8 to 80 hours, from the viewpoint of achieving more uniform mixing and higher ionic conductivity. It's time.
  • a complex is formed by the solid electrolyte raw material and the complexing agent. More specifically, the complex is formed by the interaction of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms contained in the solid electrolyte raw material with a complexing agent, such that these atoms interact with and/or without the complexing agent. It is thought that they are directly connected to each other. That is, in the manufacturing method of this embodiment, the complex obtained by mixing the solid electrolyte raw material and the complexing agent can be said to be composed of the complexing agent, a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom.
  • the complex obtained in this embodiment does not completely dissolve in the liquid complexing agent and is usually solid, so the complex is suspended in the complexing agent and the solvent used as necessary. A suspension is obtained. Therefore, the solid electrolyte manufacturing method of this embodiment corresponds to a heterogeneous system in a so-called liquid phase method.
  • solvent when mixing the solid electrolyte raw material and the complexing agent, a solvent may be further added.
  • a solvent may be further added when mixing the solid electrolyte raw material and the complexing agent.
  • separation of components may occur if the complex is easily soluble in the complexing agent. Therefore, by using a solvent in which the complex does not dissolve, elution of components in the electrolyte precursor can be suppressed.
  • the solid electrolyte manufacturing method of this embodiment is a so-called heterogeneous method, and it is preferable that the complex not completely dissolve in the liquid complexing agent but precipitate.
  • the solubility of the complex can be adjusted by adding a solvent.
  • halogen atoms are easily eluted from the complex, the desired complex can be obtained by suppressing the halogen atoms from eluting by adding a solvent.
  • a sulfide solid electrolyte having high ionic conductivity can be easily obtained through an electrolyte precursor in which components such as solid electrolyte raw materials, particularly solid electrolyte raw materials containing halogen atoms, are uniformly dispersed.
  • a solvent having a solubility parameter of 10 or less is preferably mentioned.
  • the solubility parameter is described in various documents, such as "Chemistry Handbook” (published in 2004, revised 5th edition, Maruzen Co., Ltd.), and is a value ⁇ calculated by the following formula (1). ((cal/cm 3 ) 1/2 ), which is also called Hildebrand parameter or SP value.
  • ⁇ H is the molar heat generation
  • R is the gas constant
  • T is the temperature
  • V is the molar volume.
  • solid electrolyte raw materials especially raw materials containing halogen atoms such as halogen atoms and lithium halide, and furthermore, halogen atoms constituting the complex.
  • halogen atoms for example, an aggregate of lithium halide and a complexing agent
  • the halogen atoms in particular are easily fixed in the complex, and the halogen atoms are present in a well-dispersed state in the resulting electrolyte precursor and even in the solid electrolyte, making it possible to obtain a solid electrolyte with high ionic conductivity.
  • the solvent used in this embodiment has a property that the complex does not dissolve therein.
  • the solubility parameter of the solvent is preferably 9.5 or less, more preferably 9.0 or less, and even more preferably 8.5 or less.
  • solvents that have been conventionally used in the production of solid electrolytes, such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, etc.
  • Solvents hydrocarbon solvents such as aromatic hydrocarbon solvents; alcohol solvents, ester solvents, aldehyde solvents, ketone solvents, ether solvents with 4 or more carbon atoms on one side, solvents containing carbon atoms and heteroatoms, etc.
  • solvents such as aromatic hydrocarbon solvents
  • those having a solubility parameter within the above range may be appropriately selected and used.
  • aliphatic compounds such as hexane (7.3), pentane (7.0), 2-ethylhexane, heptane (7.4), octane (7.5), decane, undecane, dodecane, tridecane, etc.
  • Hydrocarbon solvents Alicyclic hydrocarbon solvents such as cyclohexane (8.2) and methylcyclohexane; benzene, toluene (8.8), xylene (8.8), mesitylene, ethylbenzene (8.8), tert-butyl Aromatic hydrocarbon solvents such as benzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene (9.5), chlorotoluene (8.8), and bromobenzene; alcohols such as ethanol (12.7) and butanol (11.4) Solvents; aldehyde solvents such as formaldehyde, acetaldehyde (10.3), and dimethylformamide (12.1); ketone solvents such as acetone (9.9) and methyl ethyl ketone; dibutyl ether, cyclopentyl methyl ether (8.4) , tert-butyl methyl ether, anisole, and the like
  • the numerical value in parentheses in the above example is the SP value.
  • the above-mentioned examples are merely examples, and for example, those having isomers may include all isomers.
  • it may also include, for example, a substituted aliphatic group such as an alkyl group.
  • aliphatic hydrocarbon solvents aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and ether solvents are preferred, and from the viewpoint of obtaining more stable and high ionic conductivity, heptane, cyclohexane, toluene, Ethylbenzene, diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane, cyclopentyl methyl ether, tert-butyl methyl ether, and anisole are more preferred, diethyl ether, diisopropyl ether, and dibutyl ether are even more preferred, and diisopropyl ether and dibutyl ether are even more preferred. , especially cyclohexane.
  • the solvent used in this embodiment is preferably the organic solvent exemplified above, and is an organic solvent different from the complexing agent described above. In this embodiment, these solvents may be used alone or in
  • the manufacturing method of this embodiment may include drying the electrolyte precursor-containing material after obtaining the electrolyte precursor-containing material.
  • the electrolyte precursor can be heated more directly. It becomes possible to separate and remove the oxidizing agent more efficiently.
  • drying methods include filtration using a glass filter or the like, solid-liquid separation by decantation, and solid-liquid separation using a centrifuge or the like. Specifically, solid-liquid separation is performed by transferring the suspension to a container, and after the solid has precipitated, decantation is performed to remove the supernatant complexing agent and the solvent used as necessary. Filtration using a glass filter of about 200 ⁇ m, preferably 20 to 150 ⁇ m is easy.
  • the electrolyte precursor-containing material can also be dried by heating using a dryer or the like. Drying of the electrolyte precursor-containing material may be carried out under any pressure condition, such as increased pressure, normal pressure, or reduced pressure, and is preferably carried out under normal pressure or reduced pressure. In particular, considering drying at a lower temperature, it is preferable to dry under reduced pressure using a vacuum pump or the like, or even under vacuum.
  • the temperature conditions for drying may be a temperature higher than the boiling point of the remaining complexing agent or the solvent used if necessary. Specific temperature conditions cannot be generalized as they may vary depending on the type of complexing agent and solvent used, but preferably at 5°C or higher, more preferably at 10°C or higher, and even more preferably at 15°C or higher.
  • the upper limit is preferably 110°C or lower, more preferably 85°C or lower, and even more preferably 70°C or lower.
  • the pressure condition it is preferable to use normal pressure or reduced pressure, and when using reduced pressure, specifically, it is preferably 85 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa.
  • the lower limit may be a vacuum (0 KPa), and considering ease of pressure adjustment, it is preferably 1 kPa or more, more preferably 2 kPa or more, and even more preferably 3 kPa or more.
  • drying when drying is performed, drying may be performed while heating after performing the solid-liquid separation. Further, in the manufacturing method of this embodiment, drying may or may not be performed. That is, in the manufacturing method of the present embodiment, the object to be heated in the heated air stream may be an electrolyte precursor-containing substance, or may be an electrolyte precursor obtained by drying. As described above, since the electrolyte precursor can be heated more directly, the electrolyte precursor is preferable as the object to be heated.
  • the manufacturing method of this embodiment is as follows: Next to obtaining the electrolyte precursor content, heating in a heated air stream; including.
  • the electrolyte precursor-containing material obtained by obtaining the electrolyte precursor-containing material, and furthermore, the electrolyte precursor when the above drying is performed (hereinafter, the electrolyte precursor-containing material and the electrolyte precursor are collectively referred to as "heated object") ) is heated in a heated air stream to remove the complexing agent from the electrolyte precursor, that is, the complexing agent is removed from the complex formed by the solid electrolyte raw material etc. and the complexing agent.
  • a sulfide solid electrolyte is obtained.
  • heating in a heated air stream can be performed by supplying the object to be heated into an air stream in which heated gas flows, and for example, a device commercially available as a flash dryer can be used.
  • a flash dryer is a device that can heat an object with a heated airflow by supplying the object to be heated into a pipe into which the heated airflow is supplied, and the heating airflow and the object to be heated are directly connected to each other.
  • a touch, direct hot air type flash dryer is preferred.
  • a preferred example of the flash dryer is a flash dryer equipped with a cylindrical container-shaped heating part (also referred to as a "cylindrical container type flash dryer"), as shown in FIG. 1, for example.
  • the heating part is a cylindrical container, the cross-sectional area of the object to be heated and the flow path of the heated air flow will be widened, so the object to be heated will adhere to the inner wall surface and solidify, and the cross-sectional area of the flow path will be reduced due to the adhesion and solidification of the object to be heated. Even in this case, it is possible to suppress the influence on fluctuations due to flow disturbances and blockages. As a result, stable drying becomes easier. Furthermore, compared to other types described later, it is suitable for large-volume processing, and it is easy to continue operation for a long period of time, and it is easy to perform visual inspection and open cleaning, so it is excellent in maintainability.
  • the flash dryer is one that has a structure that can heat the object to be heated while swirling the heated airflow, for example, one that is provided with a dispersion plate so that the heated airflow swirls inside the piping, or one that has at least a part of the piping. It is preferable to use one having an annular shape or a semicircular shape (respectively also referred to as a "circular flash dryer” or a “semicircular flash dryer”).
  • a semicircular shape circumferenceless also referred to as a "circular flash dryer” or a “semicircular flash dryer”
  • a vertical long tube that maintains the length necessary for heating is used, and a heated airflow is introduced from the bottom of the vertical long tube and heated while flowing together with the object to be heated.
  • a vertical long tube flash dryer also referred to as a "vertical long tube flash dryer"
  • the flow direction of the object to be heated and the heated airflow can be limited to the upward direction, so it can respond to changes in the flow rate, particle size, density, etc. of the object to be heated, resulting in stable drying. dry easily.
  • the structure is simple, even if the object to be heated adheres to the inner wall, it can be easily peeled off, making it easier to cope with long-term operation.
  • the method accommodates increases in throughput and drying capacity by extending the vertical dimension, the installation area can be kept smaller compared to other types, providing an advantage in equipment installation. There is.
  • the pipe diameters of the vertical long tube portions may be the same, or may not be the same and some may be wider in order to adjust the heating state to the heated object. Or it may have a narrow portion.
  • a heated airflow may be introduced from the bottom of the container to heat the object to be heated.
  • a constriction part on the nozzle is provided at the introduction part of the heated air stream, by increasing the flow velocity and introducing the heated air stream, the object to be heated can be heated while being mixed and stirred. Efficiency can be improved.
  • any flash dryer can be used, for example, the above-mentioned cylindrical container type flash dryer may be used.
  • media particles such as ceramic balls or zirconia beads
  • the gas used for the heated air flow any gas can be used without particular limitation, and for example, inert gases such as nitrogen and argon, and various gases such as air can be used. In consideration of cost, it is preferable to use nitrogen or air, and in consideration of improving ionic conductivity, it is preferable to use nitrogen. These gases may be used alone or in combination.
  • the dew point temperature of the gas is preferably -10°C or lower, more preferably -20°C or lower, and still more preferably -30°C or lower, from the viewpoint of suppressing the quality deterioration of the sulfide solid electrolyte due to moisture contained in the gas. It is.
  • the temperature of the heated air stream is not particularly limited as long as it can be heated to the extent that the complexing agent can be removed from the electrolyte precursor, and it can vary depending on the type of complexing agent, so it cannot be generalized, but it is preferably 100°C or higher, more preferably is 105°C or higher, more preferably 110°C or higher, and the upper limit is preferably 180°C or lower, more preferably 170°C or lower, even more preferably 160°C or lower, even more preferably 155°C or lower.
  • the temperature of the heated air stream is the temperature at which the heated air stream is supplied, and for example, when the above-mentioned flash dryer is used, it is the temperature at which the heated air stream is supplied to the flash dryer. Within the above range, the complexing agent can be removed more efficiently.
  • the outlet temperature from the flash dryer will be the supply temperature to the flash dryer (temperature of the heated air stream). decreases more than Although the outlet temperature cannot be determined unconditionally compared to the supply temperature because it varies depending on the scale of the flash dryer, etc., it is usually 3° C. or more lower, further 5° C. or more lower, and can be 10° C. or more lower.
  • the temperature of the electrolyte precursor is lower than the temperature of the heated air stream because the time for heating it in the heated air stream is short and the temperature of the electrolyte precursor does not normally reach the temperature of the heated air stream.
  • the temperature of the electrolyte precursor upon heating in the heated air stream is preferably the temperature after heating in the heated air stream (i.e. also the temperature of the sulfide solid electrolyte from which the complexing agent has been removed from the electrolyte precursor).
  • the temperature is 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and the upper limit is preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower.
  • the amount of heated airflow supplied is preferably 0.1 m 3 /min or more, more preferably 0.3 m 3 /min or more, even more preferably 0.5 m 3 /min or more, and the upper limit is preferably 500 m 3 /min or less, more preferably It is 475 m 3 /min or less, more preferably 450 m 3 /min or less. Within the above range, the complexing agent can be removed more efficiently.
  • the ratio of electrolyte precursor supply amount (g/min)/heated air flow supply amount (m 3 /min) is preferably 1.0 g/m 3 or more, more preferably 1.5 g/m 3 or more, and further Preferably it is 2.0 g/m 3 or more, and the upper limit is preferably 50.0 g/m 3 or less.
  • the flow rate of the heated air stream is preferably 5 m/s or more, more preferably 7.5 m/s or more, even more preferably 9 m/s or more, and the upper limit is preferably 35 m/s or less, more preferably 30 m/s or less, and even more preferably 25 m/s. /s or less. Within the above range, the complexing agent can be removed more efficiently.
  • the heating time for heating in a heated air stream is not particularly limited as long as it is supplied to the extent that the complexing agent can be removed from the electrolyte precursor, and it can be changed depending on the type of complexing agent, the scale of the flash dryer used, etc.
  • the upper limit is preferably 1 minute or less, more preferably 50 seconds or less, still more preferably 40 seconds or less, even more preferably 15 seconds or less, particularly preferably 5 seconds or less.
  • the lower limit is usually 0.05 seconds or more, preferably 0.1 seconds or more, and more preferably 0.2 seconds or more. In this way, the heating time in the heated air stream is extremely short. Therefore, for example, the electrolyte precursor is not exposed to high temperature conditions for a long time, and deterioration due to heat can be suppressed, and a sulfide solid electrolyte having high ionic conductivity can be obtained.
  • the complexing agent By heating in the above heated air stream, the complexing agent can be removed from the electrolyte precursor, and the electrolyte precursor becomes an amorphous sulfide solid electrolyte, but all the complexing agent is removed from the electrolyte precursor. As a result, the complexing agent may remain in the amorphous sulfide solid electrolyte.
  • the content of the complexing agent contained in the sulfide solid electrolyte is preferably 0% by mass, that is, no complexing agent is contained at all, but a sulfide solid electrolyte with high ionic conductivity can be efficiently obtained.
  • the solvent may also remain.
  • the content of the solvent in this case is also the same as the numerical range of the content of the complexing agent.
  • the content of the complexing agent contained in the sulfide solid electrolyte and the solvent used as necessary is determined by dissolving the powder obtained in Examples etc. in a mixed solution of water and pentanol. was measured using a gas chromatography device (GC), and the complexing agent and high boiling point solvent were quantified using an absolute calibration curve (GC calibration curve method).
  • the manufacturing method of the present embodiment includes, after heating in the heated air stream, collecting the powder obtained by the heating.
  • the object to be heated becomes a powder obtained by removing the complexing agent from the electrolyte precursor, that is, an amorphous sulfide solid electrolyte powder by heating in a heated air flow.
  • the powder (amorphous sulfide solid electrolyte powder) obtained by removing the complexing agent from this electrolyte precursor is heated in a heated air stream and then exists floating in the heated air stream. Therefore, it is preferable in terms of the manufacturing process to collect the powder floating in the heated air stream and then perform crystallization by heating as described below.
  • a bag filter is preferably used to collect the powder floating in the heated air stream from the viewpoint of efficient collection.
  • a heated air stream containing powder (amorphous sulfide solid electrolyte powder) from which the complexing agent has been removed from the electrolyte precursor after heating in a heated air stream to a bag filter, the electrolyte precursor can be removed from the electrolyte precursor.
  • the powder (amorphous sulfide solid electrolyte powder) from which the complexing agent has been removed can be recovered.
  • the powder can be collected by connecting a bag filter downstream of the flash dryer.
  • Filters used in bag filters can be used without any particular restrictions, and include polypropylene, nylon, acrylic, polyester, cotton, wool, heat-resistant nylon, polyamide/polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polyester). Examples include filters made of materials such as (tetrafluoroethylene), and filters with functions such as electrostatic filters can also be used.
  • filters made of heat-resistant nylon, polyamide/polyimide, PPS (polyphenylene sulfide), glass fiber, and PTFE (polytetrafluoroethylene) are preferred; filters made of heat-resistant nylon, PPS (polyphenylene sulfide), and PTFE (polytetrafluoroethylene) are preferred.
  • a filter made of PTFE (polytetrafluoroethylene) is more preferable, and a filter made of PTFE (polytetrafluoroethylene) is particularly preferable.
  • the bag filter may have a brushing-off means, and for example, means using a pulsating back pressure method or a pulse jet method are preferably mentioned, and among them, means using a pulse jet method is preferable.
  • An induced draft fan may be provided in the line from the exhaust port of the bag filter to forcibly exhaust the gas exhausted from the exhaust port. By exhausting the gas using an induced draft fan or the like, filtration in the bag filter proceeds smoothly and the slurry can be dried in a shorter time.
  • the manufacturing method of the present embodiment can include further heating after heating in the heated air stream described above.
  • an amorphous sulfide solid electrolyte can be obtained from the electrolyte precursor.
  • the amorphous sulfide solid electrolyte is further heated (hereinafter also referred to as "post-heating") to crystallize the amorphous sulfide solid electrolyte. sulfide solid electrolyte.
  • the complexing agent and the solvent used as necessary may remain in the amorphous sulfide solid electrolyte obtained by heating in the above heated air flow. Further post-heating reduces the content of complexing agent and solvent remaining in the amorphous sulfide solid electrolyte, improving the quality of the sulfide solid electrolyte and making it easier to obtain high ionic conductivity. .
  • the amorphous sulfide solid electrolyte may not be formed and may remain as an electrolyte precursor. In this case, by post-heating, the complexing agent can be removed from the electrolyte precursor, and a crystalline sulfide solid electrolyte can be obtained via an amorphous sulfide solid electrolyte.
  • the heating temperature for post-heating is not particularly limited as long as it is higher than the temperature of the electrolyte precursor from which the complexing agent has been removed by heating in the above-mentioned heated air flow (i.e., the sulfide solid electrolyte).
  • the heating temperature may be determined depending on the structure of the crystalline solid electrolyte obtained by heating the amorphous sulfide solid electrolyte obtained by removing the complexing agent from the electrolyte precursor.
  • the temperature of the electrolyte precursor from which the complexing agent has been removed by heating in a heated air stream is, for example, when using a flash dryer, Means the temperature of the sulfide solid electrolyte at the outlet.
  • the heating temperature of the post-heating is determined by performing differential thermal analysis (DTA) on the amorphous solid electrolyte using a differential thermal analysis device (DTA device) at a temperature increase of 10° C./min.
  • DTA differential thermal analysis
  • the range is preferably 5°C or higher, more preferably 10°C or higher, and still more preferably 20°C or higher, and there are no particular restrictions on the upper limit.
  • the temperature should be about 40°C or lower.
  • the heating temperature for post-heating cannot be unconditionally defined as it varies depending on the structure of the crystalline solid electrolyte obtained, but is usually preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher.
  • the upper limit is not particularly limited, but is preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 250°C or lower.
  • the heating time for post-heating is not particularly limited as long as the desired crystalline solid electrolyte can be obtained, but for example, it is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. , 1 hour or more is even more preferable. Further, the upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.
  • the post-heating can be performed at normal pressure, but in order to reduce the heating temperature, it can also be performed under a reduced pressure atmosphere, or even under a vacuum atmosphere.
  • the pressure condition is preferably 85 kPa or less, more preferably 80 kPa or less, and still more preferably 70 kPa or less, and the lower limit may be vacuum (0 KPa), which allows ease of pressure adjustment.
  • the pressure is preferably 1 kPa or more, more preferably 2 kPa or more, and even more preferably 3 kPa or more.
  • the heating conditions can be made mild and it is possible to suppress the increase in size of the apparatus.
  • the post-heating is preferably performed in an inert gas atmosphere (eg, nitrogen atmosphere, argon atmosphere). This is because deterioration (for example, oxidation) of the crystalline solid electrolyte can be prevented.
  • the method of post-heating is not particularly limited, and examples thereof include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a firing furnace, and the like. Further, industrially, a horizontal dryer having a heating means and a feeding mechanism, a horizontal vibrating fluidized dryer, etc. can be used, and the selection may be made depending on the processing amount to be heated.
  • the sulfide solid electrolyte obtained by the manufacturing method of this embodiment can be either an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, as desired. That is, if post-heating is not performed, an amorphous sulfide solid electrolyte is obtained, and if post-heating is performed, a crystalline sulfide solid electrolyte is obtained.
  • the amorphous sulfide solid electrolyte obtained by the manufacturing method of the present embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and typical examples include, for example, Li 2 SP 2 Lithium sulfide, phosphorus sulfide, and halides, such as S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -LiI-LiBr, etc.
  • Solid electrolyte consisting of lithium; further containing other atoms such as oxygen atoms and silicon atoms, for example, Li 2 S-P 2 S 5 -Li 2 O-LiI, Li 2 S-SiS 2 -P 2 S Preferred examples include solid electrolytes such as 5 -LiI. From the viewpoint of obtaining higher ionic conductivity, Li 2 S-P 2 S 5 -LiI, Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -LiBr, Li 2 S-P 2 S A solid electrolyte composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as 5 -LiI-LiBr, is preferred. The types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed using, for example, an ICP emission spectrometer.
  • the amorphous sulfide solid electrolyte obtained by the production method of the present embodiment has at least Li 2 SP 2 S 5 , the molar ratio of Li 2 S and P 2 S 5 is higher. From the viewpoint of obtaining ionic conductivity, 65-85: 15-35 is preferable, 70-80: 20-30 is more preferable, and 72-78: 22-28 is still more preferable.
  • the total content of lithium sulfide and diphosphorus pentasulfide is: It is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, even more preferably 70 to 85 mol%. Further, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, even more preferably 40 to 80 mol%, and even more preferably 50 to 70 mol%. % is particularly preferred.
  • the blending ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms is 1.0 to 1.8:1.0 to 2.0:0.1 ⁇ 0.8:0.01 ⁇ 0.6 is preferable, 1.1 ⁇ 1.7:1.2 ⁇ 1.8:0.2 ⁇ 0.6:0.05 ⁇ 0.5 is more preferred, and 1.2-1.6: 1.3-1.7: 0.25-0.5: 0.08-0.4 is even more preferred.
  • the blending ratio (molar ratio) of lithium atom, sulfur atom, phosphorus atom, bromine, and iodine is 1.0 to 1.8:1.0 to 2.
  • the shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, particulate.
  • the average particle diameter (D 50 ) of the particulate amorphous sulfide solid electrolyte is, for example, 0.01 ⁇ m or more, further 0.03 ⁇ m or more, 0.05 ⁇ m or more, 0.1 ⁇ m or more, and the upper limit is It is 5 ⁇ m or less, further 3.0 ⁇ m or less, 1.5 ⁇ m or less, 1.0 ⁇ m or less, and 0.5 ⁇ m or less.
  • the sulfide solid electrolyte obtained by the manufacturing method of this embodiment does not use a jacket-type heater (vibration dryer, etc.) that was conventionally used to remove the complexing agent. Since the generation of secondary particles due to aggregation of primary particles is suppressed, the average particle diameter is within the above range. Therefore, in the manufacturing method of this embodiment, there is no need to perform pulverization (atomization) treatment.
  • crystal structure for example, Japanese Patent Application Laid-Open No. 2013-16423.
  • Li 4-x Ge 1-x P x S 4 -based thio-LISICON Region II crystal structure Examples include a crystal structure similar to the Li 4-x Ge 1-x P x S 4 -based thio-LISICON Region II (see Solid State Ionics, 177 (2006), 2721-2725).
  • the crystal structure of the crystalline sulfide solid electrolyte obtained by the manufacturing method of the present embodiment is preferably a thiolisicone region II crystal structure among the above, since higher ionic conductivity can be obtained.
  • thio-LISICON Region II type crystal structure refers to Li 4-x Ge 1-x P x S 4 -based thio-LISICON Region II (thio-LISICON Region II) type crystal structure, Li 4-x Ge 1-x Indicates that it has a crystal structure similar to P x S 4 -based thio-LISICON Region II (thio-LISICON Region II) type.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned thiolisicone region II type crystal structure, or may contain it as a main crystal, but it may contain higher ion From the viewpoint of obtaining conductivity, it is preferably contained as the main crystal.
  • "contained as a main crystal” means that the ratio of the target crystal structure to the crystal structure is 80% or more, preferably 90% or more, and 95% or more. It is more preferable.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment should not contain crystalline Li 3 PS 4 ( ⁇ -Li 3 PS 4 ) from the viewpoint of obtaining higher ionic conductivity. is preferred.
  • Li 4-x Ge 1-x P x S 4- based thiolysicone region II The diffraction peaks of the (thio-LISICON Region II ) type crystal structure
  • a crystalline sulfide solid electrolyte having the structural skeleton of Li 7 PS 6 described above and having an argyrodite crystal structure in which a portion of P is replaced with Si is also preferably mentioned.
  • the compositional formula of the argyrodite crystal structure is Li 7-x P 1-y Si y S 6 and Li 7+x P 1-y Si y S 6 (x is -0.6 to 0.6, y is 0.1 to 0.6).
  • compositional formula of the argyrodite crystal structure the compositional formula Li 7-x-2y PS 6-x-y Cl x (0.8 ⁇ x ⁇ 1.7, 0 ⁇ y ⁇ -0.25x+0.5) is also listed. It will be done.
  • examples of the compositional formula of the argyrodite crystal structure include the compositional formula Li 7-x PS 6-x Ha x (Ha is Cl or Br, and x is preferably 0.2 to 1.8).
  • the content of the complexing agent contained in the crystalline sulfide solid electrolyte is reduced by further heating than the content of the complexing agent contained in the amorphous sulfide solid electrolyte. .
  • the content of the complexing agent contained in the crystalline sulfide solid electrolyte is preferably 0% by mass, that is, it is preferable that no complexing agent is contained at all, but from the viewpoint of efficiently obtaining a sulfide solid electrolyte with high ionic conductivity. Therefore, it is usually 10% by mass or less, further 8% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, and the lower limit is about 0.01% by mass or more.
  • the solvent may also remain.
  • the content of the solvent in this case is also the same as the numerical range of the content of the complexing agent.
  • the shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, particulate.
  • the average particle diameter (D 50 ) of the particulate crystalline sulfide solid electrolyte is, for example, 0.01 ⁇ m or more, further 0.03 ⁇ m or more, 0.05 ⁇ m or more, 0.1 ⁇ m or more, and the upper limit is 5 ⁇ m. Below, furthermore, it is 3.0 micrometer or less, 1.5 micrometer or less, 1.0 micrometer or less, and 0.5 micrometer or less.
  • the sulfide solid electrolyte obtained by the manufacturing method of this embodiment does not use a jacket-type heater (vibration dryer, etc.) that was conventionally used to remove the complexing agent. Since the generation of secondary particles due to aggregation of primary particles is suppressed, the average particle diameter is within the above range. Therefore, in the manufacturing method of this embodiment, there is no need to perform pulverization (atomization) treatment.
  • the specific surface area of the sulfide solid electrolyte obtained by the manufacturing method of this embodiment is usually 10 m 2 /g or more, further 15 m 2 /g or more, 20 m 2 /g or more, or 25 m 2 /g or more. There is no particular upper limit, and it is, for example, about 50 m 2 /g or less.
  • the specific surface area is a value measured by the BET method (gas adsorption method), and nitrogen may be used as the gas (nitrogen method), krypton (krypton method) may be used as the gas, It is selected and measured as appropriate depending on the size of the surface area.
  • the sulfide solid electrolyte obtained by the manufacturing method of this embodiment has high ionic conductivity and excellent battery performance, and is therefore suitably used in batteries.
  • the sulfide solid electrolyte of this embodiment may be used for a positive electrode layer, a negative electrode layer, or an electrolyte layer. Note that each layer can be manufactured by a known method.
  • a current collector in addition to the positive electrode layer, electrolyte layer, and negative electrode layer, and a known current collector can be used.
  • a layer can be used in which a material such as Au, Pt, Al, Ti, or Cu that reacts with the solid electrolyte is coated with Au or the like.
  • Powder X-ray diffraction (XRD) measurement was carried out as follows.
  • the sulfide solid electrolyte powder obtained in the Examples and Comparative Examples was filled into a groove with a diameter of 20 mm and a depth of 0.2 mm, and was leveled with a glass to prepare a sample. This sample was sealed with a Kapton film for XRD and measured under the following conditions without exposing it to air.
  • Measuring device D2 PHASER, manufactured by Bruker Co., Ltd.
  • Tube voltage 30kV
  • Tube current 10mA
  • X-ray wavelength Cu-K ⁇ ray (1.5418 ⁇ )
  • Optical system Concentration method Slit configuration: Solar slit 4°, diverging slit 1mm, K ⁇ filter (Ni plate) used
  • the ionic conductivity was measured as follows. Circular pellets with a diameter of 10 mm (cross-sectional area S: 0.785 cm 2 ) and a height (L) of 0.1 to 0.3 cm were molded from the crystalline solid electrolytes obtained in Examples and Comparative Examples and used as samples. . Electrode terminals were taken from the top and bottom of the sample, and measurements were taken at 25° C. by the AC impedance method (frequency range: 5 MHz to 0.5 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot.
  • the content of the complexing agent contained in the sulfide solid electrolyte was measured using a gas chromatography device (GC).
  • GC gas chromatography device
  • the outline of the measurement is that a powder such as a sulfide solid electrolyte decomposed with a mixture of water and pentanol (content of pentanol in the mixture: 90% by volume) is measured by GC, and the complexing agent is measured using an absolute calibration curve. It means quantifying.
  • 0.1 g of the sample is accurately weighed and placed in a vial. Fill a vial with 10 ml of a mixture of water and pentanol to completely decompose and dissolve the sample.
  • a calibration curve 0.5 g of the complexing agent to be used is weighed out, and the volume is adjusted to 50 ml (equivalent to 10,000 ⁇ g/ml) of a mixture of water and pentanol. This is diluted and adjusted to 2500, 1000, 250, 25, 2.5 ⁇ g/ml (standard solution) and measured by GC, and a calibration curve is created using the least squares method from the peak area and the concentration of the standard solution.
  • the GC peak area value of the sample solution was applied to the calibration curve, and the concentration in the sample solution was calculated according to the following formula.
  • Electrolyte precursors used in Examples and Comparative Examples were prepared by the following method. Here, the amounts used of the solid electrolyte raw material, complexing agent, etc. were set to the required amounts in each Example and Comparative Example while keeping the ratios of amounts used as described in the following methods the same.
  • the electrolyte precursor powder obtained in the above preparation example was heated in a heated air stream using an apparatus having the configuration shown in the schematic diagram of the apparatus used for heating in a heated air stream in FIG.
  • the device shown in Fig. 1 is mainly equipped with a flash dryer (a cylindrical container type flash dryer) and a bag filter, and includes a blower and a heater for supplying heated airflow, as well as for heating objects.
  • a mixer is provided for pneumatic conveying with gas.
  • a feeder capable of supplying the object to be heated in the form of powder or slurry may be provided (not shown).
  • FIG. 1 The apparatus shown in FIG.
  • an electrolyte precursor (an object to be heated) is air-fed by gas to the bottom of the flash dryer, and a heated air stream in which the gas is heated by a heater is supplied from the bottom of the flash dryer.
  • the heated object heated in the heated air stream in the flash dryer becomes a powder (amorphous sulfide powder) from which the complexing agent has been removed from the electrolyte precursor, and the heated air stream containing this powder is passed through the downstream bag filter. supplied to Then, the powder (amorphous sulfide powder) from which the complexing agent has been removed from the electrolyte precursor is collected in a bag filter, and the heated airflow after the powder is collected is exhausted as is.
  • Example 1 A heated airflow of nitrogen heated to 115° C. was placed in a flash dryer, and the supply of the obtained electrolyte was started at 1 m 3 /min.
  • the precursor powder was air-fed into a flash dryer using 10.5 L/min of nitrogen. Heating the object to be heated (electrolyte precursor powder) in a heated air stream using a flash dryer, supplying the heated air stream discharged from the flash dryer to a bag filter, and containing the heated air stream, A powder (amorphous sulfide solid electrolyte) from which the complexing agent had been removed was recovered from the electrolyte precursor. This continued for 50 minutes (ie, the running time was 50 minutes).
  • the temperature of the heated air stream at the outlet of the flash dryer was 109°C, and the temperature of the heated air stream at the inlet of the bag filter was 61°C. Further, the content of the complexing agent contained in the recovered powder (amorphous sulfide solid electrolyte) was 43% by mass.
  • the powder (amorphous sulfide solid electrolyte) from which the complexing agent was removed from the obtained electrolyte precursor was heated (post-heating) at 110°C for 2 hours and then at 160°C for 2 hours in a Schlenk tube. , a crystalline sulfide solid electrolyte was obtained.
  • Example 2 and 3 In Example 1, the temperature and supply amount of the heated air stream supplied to the flash dryer, the operating time, and the supply amount of the electrolyte precursor powder were the same as in Example 1, except that the values shown in Table 1 were set. and the powder was collected. Table 1 shows the outlet temperature of the flash dryer, the bag filter inlet temperature, and the content of the complexing agent contained in the recovered powder (amorphous sulfide solid electrolyte). The ionic conductivity of the crystalline sulfide solid electrolyte obtained in Example 3 was measured and found to be 4.0 (mS/cm). Furthermore, the crystalline sulfide solid electrolyte obtained in Example 3 was subjected to powder XRD diffraction measurements.
  • Example 1 the temperature and supply amount of the heated air stream supplied to the flash dryer, the operating time, and the supply amount of the electrolyte precursor powder were the same as in Example 1, except that the values shown in Table 1 were set. and the powder was collected.
  • Table 1 shows the outlet temperature of the flash dryer, the bag filter inlet temperature, and the content of the complexing agent contained in the recovered powder (amorphous sulfide solid electrolyte). Further, the crystalline sulfide solid electrolytes obtained in Examples 4 to 8 were subjected to powder XRD diffraction measurements. The X-ray diffraction spectrum is shown in FIG.
  • Comparative example 1 350 g of the electrolyte precursor powder obtained in the above preparation example was heated at 110°C under vacuum for 7 hours using a vibration dryer ("VH-10 (model number)", manufactured by Chuo Kakoki Co., Ltd.). , an amorphous sulfide solid electrolyte was obtained, and heating was further performed at 170° C. for 2 hours under vacuum to obtain a crystalline sulfide solid electrolyte. Powder XRD diffraction measurements were performed on the obtained crystalline sulfide solid electrolyte. The X-ray diffraction spectrum is shown in FIG.
  • Comparative example 2 A crystalline sulfide solid electrolyte was obtained in the same manner as in Comparative Example 1, except that the electrolyte precursor powder was changed from 350 g to 550 g. Powder XRD diffraction measurements were performed on the obtained crystalline sulfide solid electrolyte. The X-ray diffraction spectrum is shown in FIG.
  • the ionic conductivity of Comparative Example 1 was 3.7 (mS/cm), and it was confirmed that the ionic conductivity was decreased due to the large amount of impurities.
  • Example 3 In Example 1, using the slurry obtained in Preparation Example, a device equipped with a fluidized bed dryer and a bag filter shown in FIG. 1 and a fluidized bed dryer using media particles and a bag filter shown in FIG. A crystalline sulfide solid electrolyte was obtained in the same manner as in Example 1 except that the apparatus was changed.
  • the temperature at which nitrogen is supplied to the fluidized bed dryer is 147°C
  • the supply rate is 2.4 m/s (the flow rate at 147°C in the cross section of the fluidized bed of a medium (media particles) with a diameter of 98 mm).
  • the slurry was supplied so that the temperature of the fluid containing gas and powder extracted from above the fluidized bed dryer was 110°C.
  • Example 9 In Example 1, the temperature and supply amount of the heated air stream supplied to the flash dryer, the operating time, and the supply amount of the electrolyte precursor powder were the same as in Example 1, except that the values shown in Table 2 were set. and the powder was collected. Table 2 shows the outlet temperature of the flash dryer, the bag filter inlet temperature, and the content of the complexing agent contained in the recovered powder (amorphous sulfide solid electrolyte). Further, powder XRD diffraction measurements were performed on the crystalline sulfide solid electrolytes obtained in Examples 9 to 15. The X-ray diffraction spectrum is shown in FIG.
  • Examples 9 to 15 are examples in which the amount of electrolyte precursor supplied was increased compared to Examples 1 to 8. From the results of Examples 9 to 15, even if the scale is increased, by heating in the heated air stream while maintaining the supply amount of the heated air stream, especially the flow rate, within a certain range, the air flow dryer can be heated in a very short time at the outlet of the flash dryer. It was confirmed that the content of the complexing agent can be reduced, and a high quality sulfide solid electrolyte with few impurities and high ionic conductivity can be obtained.
  • a sulfide solid electrolyte with high ionic conductivity can be efficiently manufactured.
  • the complexing agent can be easily removed from the electrolyte precursor-containing material regardless of the scale, as long as the supply amount of the heated air stream, especially the flow rate, is maintained within a certain range. It is also possible to correspond to The sulfide solid electrolyte of this embodiment obtained by the manufacturing method of this embodiment is suitable for use in batteries, especially batteries used in information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones. It will be done.

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