WO2024122518A1 - Électrolyte solide au sulfure et procédé de production d'électrolyte solide au sulfure - Google Patents

Électrolyte solide au sulfure et procédé de production d'électrolyte solide au sulfure Download PDF

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WO2024122518A1
WO2024122518A1 PCT/JP2023/043372 JP2023043372W WO2024122518A1 WO 2024122518 A1 WO2024122518 A1 WO 2024122518A1 JP 2023043372 W JP2023043372 W JP 2023043372W WO 2024122518 A1 WO2024122518 A1 WO 2024122518A1
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solid electrolyte
atoms
sulfide solid
sulfide
raw material
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PCT/JP2023/043372
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English (en)
Japanese (ja)
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恒太 寺井
太 宇都野
弘幸 樋口
清治 忠永
章 三浦
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出光興産株式会社
国立大学法人北海道大学
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/14—Sulfur, selenium, or tellurium compounds of phosphorus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/10—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances sulfides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials

Definitions

  • the present invention relates to a sulfide solid electrolyte and a method for producing a sulfide solid electrolyte.
  • batteries used for such purposes used electrolytes containing flammable organic solvents, but by making the battery all-solid-state, flammable organic solvents are not used in the battery, safety devices can be simplified, and manufacturing costs and productivity are excellent. Therefore, development is being carried out on batteries in which the electrolyte is replaced with a solid electrolyte layer, i.e., all-solid-state batteries.
  • Solid electrolytes used in solid electrolyte layers are broadly divided into solid-phase and liquid-phase methods, and liquid-phase methods include homogeneous methods in which the solid electrolyte material is completely dissolved in a solvent, and heterogeneous methods in which the solid electrolyte material is not completely dissolved and a solid-liquid coexistence suspension is formed.
  • a solid-phase method is known in which raw materials such as lithium sulfide and diphosphorus pentasulfide are mechanically milled using a ball mill, bead mill, or other device, and then heated as necessary to produce an amorphous or crystalline solid electrolyte (see, for example, Patent Document 1).
  • a sulfide solid electrolyte having an LGPS type crystal structure is a type of solid-phase method in which the solid raw materials lithium sulfide, diphosphorus pentasulfide, and diphosphorus pentoxide are fired at 700 to 950°C, melted, and then rapidly cooled, a so-called melt-quenching method (see, for example, Patent Documents 5 and 6).
  • a method for producing a sulfide solid electrolyte having an LGPS type crystal structure composed of lithium, germanium, phosphorus, sulfur, and oxygen atoms is a solid-phase method in which the solid raw materials are pulverized using a vibrating mill to produce an amorphous sulfide solid electrolyte, which is then heated to crystallize (see, for example, Patent Document 7).
  • the present invention was made in consideration of these circumstances, and aims to provide a sulfide solid electrolyte that contains lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms and has high water resistance with high production efficiency.
  • the method for producing a sulfide solid electrolyte according to the present invention includes the steps of: A raw material containing lithium atoms, phosphorus atoms, and sulfur atoms is mixed with a protic organic solvent containing oxygen atoms to prepare a solution; including, A method for producing a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms, It is.
  • a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms and having high water resistance can be provided with high production efficiency.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 1.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 2.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 3.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 4.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 5.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 6.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 7.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 8.
  • 1 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in Example 9.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 10.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 11.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 12.
  • 1 is an X-ray diffraction pattern of the crystalline sulfide solid electrolyte obtained in Example 13.
  • 1 is an X-ray diffraction pattern of the powder obtained after drying in Comparative Example 1.
  • 1 is an X-ray diffraction pattern of the powder obtained after heating in Comparative Example 1.
  • 1 is an explanatory diagram for determining the half-width of a diffraction peak.
  • 1 is an explanatory diagram for determining the half-width of a diffraction peak.
  • 1 shows solid-state 31 P-NMR spectra of the crystalline sulfide solid electrolytes obtained in Examples 4 and 9.
  • 1 is a CV curve measured by the method of CV measurement 1 of the crystalline sulfide solid electrolyte obtained in Example 11.
  • 1 is a CV curve measured by the CV measurement 2 method for the crystalline sulfide solid electrolyte obtained in Example 11.
  • this embodiment an embodiment of the present invention (hereinafter, sometimes referred to as “this embodiment") will be described.
  • the upper and lower limit values of the numerical ranges "greater than or equal to,” “less than or equal to,” and “to” are values that can be combined in any way, and the numerical values in the examples can also be used as the upper and lower limit values.
  • regulations that are considered to be preferred can be adopted in any way. In other words, one regulation that is considered to be preferred can be adopted in combination with one or more other regulations that are considered to be preferred. It can be said that a combination of preferred things is more preferable.
  • the use of a pulverizer also requires a large amount of energy consumption and the production efficiency is reduced. Furthermore, since the particles aggregate and solidify when sintered at a high temperature, it is necessary to pulverize the solid electrolyte with a strong force during battery production, which increases the energy consumption and further reduces the production efficiency. In addition, as the demand for solid electrolytes increases, there is a demand for more efficient mass production, but it is difficult to respond to mass production, especially when a pulverizer is used.
  • the present inventors focused on the conventional liquid phase method for producing a sulfide solid electrolyte disclosed in the above Patent Documents 2 to 4, Non-Patent Document 1, etc., and investigated whether the liquid phase method could be applied to the production of a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms.
  • the sulfide solid electrolyte having an LGPS type crystal structure composed of lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms described in Patent Documents 5 and 6 uses lithium sulfide, diphosphorus pentasulfide, and diphosphorus pentoxide as starting materials
  • the sulfide solid electrolyte having an LGPS type crystal structure composed of lithium atoms, germanium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms described in Patent Document 7 uses lithium sulfide, lithium oxide, diphosphorus pentasulfide, and germanium sulfide as starting materials.
  • the sulfide solid electrolytes having an LGPS type crystal structure described in Patent Documents 5 to 7 are composed of atoms supplied from the solid raw material that is the starting material.
  • the present inventors have found that when a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms is used in combination with a protic organic solvent having oxygen atoms, the oxygen atoms contained in the protic organic solvent contribute to the formation of the crystal structure of the sulfide solid electrolyte.
  • the method for producing a sulfide solid electrolyte of this embodiment includes mixing a raw material content containing lithium atoms, phosphorus atoms, and sulfur atoms with a protic organic solvent containing oxygen atoms. By using a protic organic solvent containing oxygen atoms, the raw material content dissolves in the protic organic solvent to produce a solution.
  • the oxygen atoms contained in the protic organic solvent react with each atom contained in the raw material content, and the oxygen atoms are incorporated as atoms that constitute the sulfide solid electrolyte while promoting the reaction of the raw materials, resulting in the production of a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms.
  • a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms can be obtained by simply mixing, without employing any firing at high temperatures or pulverization with a pulverizer, in such an extremely simple manner. Therefore, according to the manufacturing method of this embodiment, a sulfide solid electrolyte can be manufactured with high production efficiency, and mass production is facilitated by employing a liquid phase method.
  • the obtained sulfide solid electrolyte has excellent water resistance, for example, suppressing the generation of hydrogen sulfide and suppressing deterioration of battery performance even when it comes into contact with moisture (e.g., moisture in the air) during battery production and use as a battery. It also has excellent electrochemical stability when used as a battery.
  • a method for producing a sulfide solid electrolyte according to a second aspect of the present embodiment is the same as the first aspect,
  • the raw material containing lithium atoms, phosphorus atoms, and sulfur atoms contains lithium sulfide and phosphorus sulfide. That is it.
  • the raw material contents used in the manufacturing method of this embodiment preferably include lithium sulfide and phosphorus sulfide.
  • the reaction of the raw materials is promoted while incorporating oxygen atoms contained in the protic organic solvent, making it possible to manufacture a sulfide solid electrolyte with high production efficiency.
  • a method for producing a sulfide solid electrolyte according to a third aspect of the present embodiment is the same as the second aspect,
  • the amount of lithium sulfide blended with respect to the total amount of the lithium sulfide and the phosphorus sulfide is 45.0 mol% or more and 78.0 mol% or less. That is it.
  • lithium sulfide and phosphorus sulfide which are preferably used as the raw material contents used in the production method of this embodiment, by using these raw materials in a specific range, the reaction of the raw materials is promoted while oxygen atoms contained in the protic organic solvent are incorporated, making it possible to produce a sulfide solid electrolyte with high production efficiency. Furthermore, when lithium sulfide and phosphorus sulfide are used in such a ratio, the PS 4 3- structure is efficiently formed, and high ionic conductivity is obtained.
  • a method for producing a sulfide solid electrolyte according to a fourth aspect of the present embodiment is any one of the first to third aspects,
  • the raw material content does not contain a raw material containing an oxygen atom. That is it.
  • the reaction of the raw materials proceeds while incorporating oxygen atoms contained in the protic organic solvent, and thus a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms is obtained. Therefore, even if the raw material contents do not contain raw materials containing oxygen atoms, a sulfide solid electrolyte containing oxygen atoms can be obtained.
  • the fourth form of this embodiment clarifies this point.
  • a method for producing a sulfide solid electrolyte according to a fifth aspect of the present embodiment includes the steps of:
  • the step of preparing the solution includes mixing a raw material containing lithium atoms and sulfur atoms with the protic organic solvent containing oxygen atoms, and then adding a raw material containing phosphorus atoms and sulfur atoms and mixing the mixture.
  • the sixth aspect of the present embodiment relates to a method for producing a sulfide solid electrolyte, and in the first aspect, The step of preparing the solution includes mixing a raw material containing lithium atoms and sulfur atoms, a raw material containing phosphorus atoms and sulfur atoms, and a protic organic solvent containing oxygen atoms; That is it.
  • All of the forms specify the order in which the raw material contents and the protic organic solvent are mixed, and by mixing in the order of these forms, the oxygen atoms contained in the protic organic solvent are efficiently incorporated while promoting the reaction of the raw materials, making it possible to produce a sulfide solid electrolyte with high production efficiency. From these forms, it can be said that in the production method of this embodiment, it is preferable to first mix the protic organic solvent containing oxygen atoms with the raw material contents containing lithium atoms and sulfur atoms.
  • a method for producing a sulfide solid electrolyte according to a seventh aspect of the present embodiment is the same as the fifth or sixth aspect,
  • the raw material content containing lithium atoms and sulfur atoms contains lithium sulfide, and the raw material content containing phosphorus atoms and sulfur atoms contains phosphorus sulfide. That is it.
  • lithium sulfide and phosphorus sulfide are added as raw materials in a specified order and mixed with a protic organic solvent, which promotes the reaction of the raw materials while efficiently incorporating oxygen atoms contained in the protic organic solvent, making it possible to produce a sulfide solid electrolyte with high production efficiency.
  • a method for producing a sulfide solid electrolyte according to an eighth aspect of the present embodiment is any one of the first to seventh aspects,
  • the protic organic solvent containing an oxygen atom is at least one solvent selected from the group consisting of an alcohol solvent, a nitro group-containing solvent, and a carboxylic acid solvent. That is it.
  • the oxygen atoms contained in the protic organic solvent are efficiently incorporated while promoting the reaction of the raw materials, making it possible to produce sulfide solid electrolytes with high production efficiency.
  • a method for producing a sulfide solid electrolyte according to a ninth aspect of the present embodiment is any one of the first to eighth aspects, preparing the solution, and then further heating the solution.
  • the method for producing a sulfide solid electrolyte according to a tenth aspect is the same as the ninth aspect,
  • the heating temperature in the heating is 200° C. or more and 450° C. or less. That is it.
  • Further heating produces a crystalline sulfide solid electrolyte.
  • further heating is heating for crystallization. If a crystalline sulfide solid electrolyte is desired, further heating is sufficient, and in that case, a sulfide solid electrolyte with a better crystal structure can be efficiently obtained by setting the temperature to 200°C or higher and 450°C or lower.
  • a method for producing a sulfide solid electrolyte according to an eleventh aspect of the present embodiment is any one of the first to tenth aspects,
  • the sulfide solid electrolyte has an LGPS type crystal structure. That is it.
  • Sulfide solid electrolytes having an LGPS crystal structure are known to have extremely high ionic conductivity among sulfide solid electrolytes containing oxygen atoms, and are preferable as the sulfide solid electrolyte to be obtained by the manufacturing method of this embodiment.
  • the sulfide solid electrolyte of this embodiment it is not clear which crystal structure produces the peak of the other crystal structure, but it is believed that other crystal structures other than the LGPS crystal structure exist depending on the way oxygen atoms are present.
  • the sulfide solid electrolyte of this embodiment is produced by the above-mentioned method for producing a sulfide solid electrolyte, it is believed that when the reaction of the raw materials proceeds while oxygen atoms contained in the protic organic solvent are taken in, the other crystal structure is generated by the oxygen atoms and raw materials that did not contribute to the formation of the LGPS crystal structure.
  • the sulfide solid electrolyte according to the fifteenth aspect is any one of the twelfth to fourteenth aspects,
  • the intensity ratio ( I33.9 / I31.0 ) of the other crystal structures is within the above range, the water resistance and electrochemical stability are improved.
  • This tendency of peak intensity is particularly noticeable in the sulfide solid electrolyte produced by the above-mentioned method for producing a sulfide solid electrolyte. This is considered to be due to the fact that, when the production method of this embodiment is adopted, oxygen atoms contained in the protic organic solvent are more easily incorporated into the crystal structure than when an oxide containing oxygen atoms is used as a raw material.
  • a sulfide solid electrolyte according to a seventeenth aspect of the present embodiment is any one of the twelfth to sixteenth aspects,
  • the sulfide solid electrolyte according to an eighteenth aspect of the present embodiment is any one of the twelfth to seventeenth aspects, A peak due to PSO 3 3- was observed at 34.0 ⁇ 5.0 ppm by solid-state 31 P-NMR measurement.
  • the sulfide solid electrolyte according to the nineteenth aspect is any one of the twelfth to eighteenth aspects, A peak due to PO 4 3- was observed at 6.0 ⁇ 5.0 ppm by solid-state 31 P-NMR measurement.
  • the sulfide solid electrolyte according to the twentieth aspect is any one of the twelfth to nineteenth aspects, A peak due to PS 2 O 2 3- was observed at 67.0 ⁇ 5.0 ppm by solid-state 31 P-NMR measurement. That is it.
  • the sulfide solid electrolyte of this embodiment has an LGPS-type crystal structure that contains lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms.
  • the peaks in the sixteenth and seventeenth forms are both peaks that are expressed by the LGPS-type crystal structure.
  • a sulfide solid electrolyte according to a twenty-first aspect of the present embodiment is any one of the twelfth to twentieth aspects, the ratio (M S /M P ) of the number of moles of sulfur atoms (M S ) to the number of moles of phosphorus atoms (M P ) is 0.5 or more and 4.0 or less;
  • the sulfide solid electrolyte according to the twenty-second aspect is any one of the twelfth to twenty-first aspects, a ratio ( ML / MP ) of the number of moles of lithium atoms ( ML ) to the number of moles of phosphorus atoms ( MP ) is 2.3 or more and 3.9 or less; That is it.
  • the LGPS-type crystal structure and other crystal structures are easily formed, and as a result, excellent ionic conductivity, water resistance, and electrochemical stability are easily obtained.
  • a sulfide solid electrolyte according to a twenty-third aspect of the present embodiment is any one of the twelfth to twenty-second aspects, Further, the carbon atom That is it.
  • the sulfide solid electrolyte of this embodiment is preferably obtained by the manufacturing method of this embodiment.
  • a protic organic solvent containing oxygen atoms is used, and therefore carbon atoms contained in the protic organic solvent may remain.
  • the sulfide solid electrolyte of this embodiment contains carbon atoms but no raw material containing carbon atoms is used as the raw material, the sulfide solid electrolyte of this embodiment can be said to be obtained by the manufacturing method of this embodiment.
  • Solid electrolyte refers to an electrolyte that maintains a solid state at 25° C. under a nitrogen atmosphere.
  • the sulfide solid electrolyte in this embodiment is a solid electrolyte that contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms and has ionic conductivity due to lithium atoms.
  • sulfur atoms it is called a sulfide solid electrolyte.
  • solid electrolyte includes both amorphous solid electrolytes and crystalline solid electrolytes.
  • the crystalline solid electrolyte is a solid electrolyte in which a peak derived from the solid electrolyte is observed in the X-ray diffraction pattern in the X-ray diffraction measurement, regardless of the presence or absence of a peak derived from the raw material of the solid electrolyte. That is, the crystalline solid electrolyte includes a crystal structure derived from the solid electrolyte, and a part of the crystal structure may be derived from the solid electrolyte, or the whole of the crystal structure may be derived from the solid electrolyte.
  • the crystalline solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte to a crystallization temperature or higher.
  • the amorphous solid electrolyte refers to an electrolyte that has a halo pattern in which no peaks other than those derived from the material are substantially observed in an X-ray diffraction pattern in an X-ray diffraction measurement, regardless of whether or not there is a peak derived from the raw material of the solid electrolyte.
  • the method for producing the sulfide solid electrolyte of the present embodiment includes the steps of: A raw material containing lithium atoms, phosphorus atoms, and sulfur atoms is mixed with a protic organic solvent containing oxygen atoms to prepare a solution; including, A method for producing a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms, It is.
  • the manufacturing method of the present embodiment includes preparing a solution by mixing a raw material containing lithium atoms, phosphorus atoms, and sulfur atoms with a protic organic solvent containing oxygen atoms (hereinafter, may be simply referred to as a "protic organic solvent").
  • a protic organic solvent containing oxygen atoms
  • the raw material content used in this embodiment contains lithium atoms, sulfur atoms, and phosphorus atoms. More specifically, it is a content containing a substance (hereinafter also referred to as "raw material") containing one or more types selected from the group consisting of these atoms, and it is preferable that the raw material content contains two or more types of raw materials.
  • raw material include raw materials containing at least two types of atoms selected from the above-mentioned atoms, such as lithium sulfide; phosphorus sulfide such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ); and raw materials consisting of one type of atom selected from the above-mentioned atoms, such as elemental phosphorus and elemental sulfur.
  • lithium sulfide and phosphorus sulfides such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ) are preferred, and among phosphorus sulfides, diphosphorus pentasulfide (P 2 S 5 ) is preferred.
  • the raw material may also include a substance containing a halogen atom, such as lithium halides, such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide, and elemental halogens, such as fluorine (F 2 ), chlorine (Cl 2 ), bromine (Br 2 ), and iodine (I 2 ).
  • a halogen atom such as lithium halides, such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide
  • elemental halogens such as fluorine (F 2 ), chlorine (Cl 2 ), bromine (Br 2 ), and iodine (I 2 ).
  • the raw materials include substances containing at least one atom selected from the group consisting of lithium atoms, phosphorus atoms, and sulfur atoms, such as phosphorus halides such as 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 ), and various phosphorus iodides (PI 3 , P 2 I 4 ); thiophosphoryl fluoride (PSF 3 ), thiophosphoryl chloride (PSCl 3 ), thiophosphoryl bromide (PSBr 3 ), thiophosphoryl iodide (PSI 3 ), thiophosphoryl fluoride dichloride (PSCl 2 F), and thiophosphoryl fluoride dibromide (PSBr 2 I 4 ).
  • phosphorus halides such as various phosphorus fluorides (PF 3 , PF 5 ), various
  • thiophosphoryl halides such as thiophosphoryl halides F); 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; metal sulfides such as silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, tin sulfide (SnS, SnS 2 ), aluminum sulfide, and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium, such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride, and sodium bromide; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin
  • a material that acts as a solid electrolyte such as Li 3 PS 4 or Li 7 P 3 S 11 , which includes a PS 4 structure, can also be used as a raw material.
  • Li 3 PS 4 when Li 3 PS 4 is used as a raw material, Li 3 PS 4 may be prepared in advance by manufacturing or the like, and this may be used as a raw material.
  • raw materials containing oxygen atoms such as P 2 O 5 , Li 2 O, LiOH, etc. can be used, but they do not have to be used.
  • the raw material does not contain raw materials containing oxygen atoms.
  • the manufacturing method of this embodiment is different from conventional manufacturing methods in that the protic organic solvent containing oxygen atoms is employed, and the reaction of the raw materials proceeds while the oxygen atoms contained in the protic organic solvent are efficiently incorporated, thereby making it possible to obtain a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms. Therefore, even if a raw material containing oxygen atoms is not used, a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms can be obtained.
  • the raw material such as lithium sulfide used in this embodiment is preferably in the form of particles.
  • the average particle size ( D50 ) of the raw material particles may be, for example, 0.1 ⁇ m to 1000 ⁇ m, 0.5 ⁇ m to 100 ⁇ m, or 1 ⁇ m to 20 ⁇ m, taking into consideration the reaction of the raw material, handling, etc.
  • the average particle size ( D50 ) is the particle size that reaches 50% (volume basis) of the total when the particle size distribution cumulative curve is drawn, starting from the smallest particle, and the volume distribution is the average particle size that can be measured using, for example, a laser diffraction/scattering type particle size distribution measuring device.
  • the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 45.0 mol% or more, more preferably 55.0 mol% or more, even more preferably 65.0 mol% or more, even more preferably 67.0 mol% or more, and particularly preferably 70.0 mol% or more, from the viewpoint of obtaining higher water resistance, electrochemical stability, and higher ionic conductivity, and the upper limit is preferably 80.0 mol% or less, more preferably 78.0 mol% or less, and even more preferably 76.0 mol% or less.
  • Representative numerical ranges are preferably 45.0 to 80.0 mol%, 55.0 to 78.0 mol%, 65.0 to 78.0 mol%, 67.0 to 78.0 mol%, 70.0 to 78.0 mol%, and 70.0 to 76.0 mol%.
  • a protic organic solvent containing oxygen atoms is used.
  • the raw material contents are dissolved to form a solution, and the oxygen atoms contained in the protic organic solvent in the solution react with each atom contained in the raw material contents, so that the oxygen atoms are incorporated as atoms constituting the sulfide solid electrolyte while the raw material reaction proceeds, and a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms is produced.
  • the protic organic solvent containing an oxygen atom can be any organic solvent that contains an oxygen atom and has protic properties (that is, the ability to donate hydrogen ions (protons)).
  • Preferred examples of the protic organic solvent containing an oxygen atom include alcohol solvents, nitro group-containing solvents, and carboxylic acid solvents.
  • the alcohol solvent include various propanols such as methanol, ethanol, propanol, and isopropanol (hereinafter, compounds having a specific carbon number, including linear, branched, and isomers thereof, may be abbreviated as "various types"), various butanols, various decanols, and other aliphatic alcohol solvents; monohydric alcohols such as alicyclic alcohol solvents such as cyclopentanol and cyclohexanol, and polyhydric alcohols such as ethylene glycol.
  • the above-mentioned solvents can be used alone or in combination.
  • monohydric alcohols are preferred, and monohydric aliphatic alcohol solvents are more preferred.
  • the various butanols mentioned above can be primary alcohols such as 1-butanol, secondary alcohols such as 2-butanol, and tertiary alcohols such as 2-methyl-2-propanol, with primary alcohols being preferred.
  • the number of carbon atoms in the alcohol solvent is preferably 1 or more, more preferably 2 or more, with the upper limit being preferably 8 or less, more preferably 6 or less, even more preferably 4 or less, and even more preferably 3 or less.
  • a carbon number of 2, i.e., ethanol is preferred.
  • Representative numerical ranges for the number of carbon atoms are preferably 1 to 8, 1 to 6, 1 to 4, 2 to 4, or 2 to 3.
  • nitro group-containing solvent examples include nitroalkanes such as nitromethane and nitroethane
  • carboxylic acid solvent include formic acid, acetic acid, propionic acid, etc.
  • the nitro group-containing solvent and the carboxylic acid solvent for example, the above-listed solvents can be used alone or in combination.
  • the carbon number of the nitro group-containing solvent and the carboxylic acid solvent is preferably 1 or more, and the upper limit is preferably 6 or less, more preferably 4 or less, even more preferably 3 or less, and still more preferably 2 or less.
  • a solvent other than the above-mentioned oxygen atom-containing protic organic solvent can also be used.
  • examples of such a solvent include aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.
  • aliphatic hydrocarbon solvents include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane;
  • alicyclic hydrocarbon solvents include cyclohexane and methylcyclohexane;
  • aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, chlorobenzene, chlorotoluene, and bromobenzene. These solvents can be used alone or in combination.
  • those having isomers may include all isomers.
  • those substituted with halogen atoms, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents may also include those substituted with aliphatic groups such as alkyl groups.
  • the above-mentioned raw material ingredients are mixed with a protic organic solvent to prepare a solution.
  • a protic organic solvent there is no particular limitation on the method of mixing the raw material content and the protic organic solvent, and the raw material content and the protic organic solvent can be mixed by feeding them into a device capable of mixing the raw material content and the protic organic solvent.
  • the order in which the raw material ingredients are added is not particularly limited, but from the viewpoint of efficiently incorporating oxygen atoms contained in the protic organic solvent and promoting the reaction of the raw materials, and producing a sulfide solid electrolyte with high production efficiency, the following mixing methods (1) and (2) are preferable.
  • Mixing method (1) Mixing a raw material containing lithium atoms and sulfur atoms with the protic organic solvent containing oxygen atoms, and then adding a raw material containing phosphorus atoms and sulfur atoms and mixing.
  • Mixing method (2) A raw material containing lithium atoms and sulfur atoms, a raw material containing phosphorus atoms and sulfur atoms, and the protic organic solvent containing oxygen atoms are mixed.
  • two kinds of raw material containing materials that is, a raw material containing lithium atoms and sulfur atoms and a raw material containing phosphorus atoms and sulfur atoms, are added separately and mixed with a protic organic solvent.
  • the raw material containing lithium atoms and sulfur atoms is mixed with the protic organic solvent first.
  • Two types of raw material containing materials that is, a raw material containing lithium atoms and sulfur atoms and a raw material containing phosphorus atoms and sulfur atoms, are simultaneously mixed with a protic organic solvent.
  • a raw material containing lithium atoms and sulfur atoms can be used from among the raw materials contained in the raw material content, and among them, it is preferable to contain lithium sulfide, and it is preferable to be lithium sulfide.
  • the raw material content containing phosphorus atoms and sulfur atoms those containing lithium atoms and sulfur atoms can be used from among the raw materials contained in the raw material content, and among these, it is preferable to contain phosphorus sulfide, more preferably diphosphorus pentasulfide, and even more preferably diphosphorus pentasulfide.
  • the other raw materials when other raw materials are used than the raw material contents containing lithium atoms and sulfur atoms and the raw material contents containing phosphorus atoms and sulfur atoms, the other raw materials may be added at any time.
  • the amounts of lithium sulfide and phosphorus sulfide (diphosphorus pentasulfide) used are as explained in the raw material contents.
  • the amount of oxygen atoms in the sulfide solid electrolyte can be controlled by adjusting the amount of protic organic solvent containing oxygen atoms. For example, by reducing the total amount of protic organic solvent relative to the raw materials in the above process, the amount of oxygen that enters the structure can be reduced while promoting the reaction of the raw materials.
  • a mechanical stirring mixer equipped with stirring blades in a tank.
  • mechanical stirring mixers include high-speed stirring mixers and double-arm mixers, and high-speed stirring mixers are preferably used from the viewpoint of increasing the uniformity of the raw material contents in the mixture of the raw material contents and the protic organic solvent, thereby promoting dissolution, and efficiently incorporating oxygen atoms contained in the protic organic solvent while promoting the reaction of the raw materials, thereby producing a sulfide solid electrolyte with high production efficiency.
  • high-speed stirring mixers include vertical axis rotary mixers and horizontal axis rotary mixers, and either type of mixer may be used.
  • the shapes of the impellers used in the mechanically stirred mixer include anchor type, blade type, arm type, ribbon type, multi-stage blade type, double arm type, shovel type, double-shaft blade type, flat blade type, C-shaped blade type, etc.
  • Shovel type, flat blade type, C-shaped blade type, etc. are preferred from the viewpoint of increasing the uniformity of the raw material contents in the mixture of the raw material contents and the protic organic solvent to promote dissolution, and promoting the reaction of the raw materials while efficiently incorporating oxygen atoms contained in the protic organic solvent, thereby producing a sulfide solid electrolyte with high production efficiency.
  • the mechanical stirring mixer it is preferable to provide a circulation line that discharges the stirring target outside the mixer and then returns it to the inside of the mixer, which makes it possible to produce the sulfide solid electrolyte with even higher production efficiency.
  • the location of the circulation line is not particularly limited, but it is preferable to install it at a location where it is discharged from the bottom of the mixer and returned to the top of the mixer. This makes it easier to mix the raw materials that tend to settle uniformly by carrying them on the convection caused by the circulation, which can promote the dissolution of the raw material contents.
  • the return port is located below the liquid surface of the object to be mixed. This can prevent the object to be mixed from splashing and adhering to the wall surface inside the mixer.
  • the temperature conditions when mixing the raw material ingredients and the protic organic solvent are not particularly limited, and are, for example, usually ⁇ 30 to 80° C. From the viewpoint of increasing the uniformity of the raw material ingredients to promote dissolution, and efficiently incorporating oxygen atoms contained in the protic organic solvent to promote the reaction of the raw materials and produce a sulfide solid electrolyte with high production efficiency, the temperature is preferably ⁇ 10 to 60° C., more preferably 0 to 50° C., and even more preferably about room temperature (23° C.) (for example, about room temperature ⁇ 5° C.).
  • the mixing time is usually 30 seconds to 10 hours, and from the same viewpoint as the above temperature condition, it is preferably 1 minute to 1 hour, more preferably 2 to 30 minutes, and even more preferably 3 to 15 minutes.
  • the total time of the multiple mixings may be within the above mixing time range.
  • the manufacturing method of this embodiment includes mixing the raw material content with a protic organic solvent, that is, it is sufficient to mix the raw material content with the protic organic solvent, and pulverization is not required, so the method may not use equipment generally used for the purpose of pulverizing the raw material content, such as a media-type pulverizer such as a ball mill or a bead mill.
  • the raw material content and the protic organic solvent are simply mixed to prepare a solution, and the oxygen atoms contained in the protic organic solvent react with each atom contained in the raw material content in the solution.
  • the oxygen atoms are efficiently incorporated as atoms constituting the sulfide solid electrolyte, and the reaction of the raw materials is promoted, and a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms is obtained.
  • a grinder may be used to atomize the raw materials contained in the raw material content and the obtained sulfide solid electrolyte, but it is preferable not to use a grinder when mixing the raw material content with the protic organic solvent.
  • the manufacturing method of the present embodiment preferably further includes heating. Heating improves the crystallinity and provides a high-quality crystalline sulfide solid electrolyte.
  • the solution obtained by preparing the above solution may be heated, or the solute dissolved in the solution, i.e., the sulfide solid electrolyte, may be precipitated by drying as described below, and then the solution may be heated.
  • the solute is precipitated simply by drying, the resulting sulfide solid electrolyte is amorphous, and when the solute is heated for crystallization, a crystalline sulfide solid electrolyte is obtained.
  • the heating temperature is not particularly limited as long as it is a temperature at which a crystalline sulfide solid electrolyte can be obtained, and cannot be generally stated as it can vary depending on the crystal structure of the crystalline sulfide solid electrolyte obtained, but is preferably 130°C or higher, more preferably 150°C or higher, even more preferably 200°C or higher, and even more preferably 250°C or higher, and the upper limit is preferably 600°C or lower, more preferably 500°C or lower, even more preferably 425°C or lower, even more preferably 375°C or lower, and particularly preferably 325°C or lower.
  • Representative numerical ranges are preferably 130 to 600°C, 150 to 600°C, 150°C to 550°C, 200 to 500°C, 200 to 425°C, 200 to 375°C, 200 to 325°C, 250 to 375°C, and 250 to 325°C.
  • the heating time is not particularly limited as long as the desired crystalline solid electrolyte is obtained, but is preferably at least 1 minute, more preferably at least 10 minutes, even more preferably at least 30 minutes, and even more preferably at least 1 hour.
  • the upper limit of the heating time is not particularly limited, but is preferably at most 24 hours, more preferably at most 10 hours, even more preferably at most 5 hours, and even more preferably at most 3 hours.
  • the heating can be carried out at normal pressure, but in order to reduce the heating temperature, it can also be carried out under a reduced pressure atmosphere or even under a vacuum atmosphere.
  • the pressure when heating is performed under a reduced pressure atmosphere, the pressure is preferably 85 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa or less, and the lower limit may be a vacuum (0 KPa), and in consideration of 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 the size of the apparatus can be suppressed.
  • the heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere), because this can prevent deterioration (e.g., oxidation) of the crystalline solid electrolyte.
  • an inert gas atmosphere e.g., a nitrogen atmosphere or an argon atmosphere
  • the heating method is not particularly limited, and examples thereof include a method using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a baking furnace, etc.
  • a horizontal dryer having a heating means and a feeding mechanism, a horizontal vibration fluidized dryer, etc. may be used, and may be selected according to the amount of processing to be heated.
  • the manufacturing method of the present embodiment may include drying the solution after preparing the above-mentioned solution.
  • the solvent in the solution can be volatilized and removed, and a powder solute, i.e., an amorphous sulfide solid electrolyte, can be obtained.
  • the solute i.e., the sulfide solid electrolyte
  • the solute can be heated more directly, and therefore a crystalline sulfide solid electrolyte can be obtained more efficiently.
  • the drying method includes a method of drying by heating using a dryer, etc.
  • a method of drying by heating the solvent contained in the solution is volatilized, and the solute is easily obtained. Drying by heating may be performed under any pressure condition, such as under pressure, normal pressure, or reduced pressure, and is preferably performed under normal pressure or reduced pressure. In particular, when drying at a lower temperature is required, it is preferable to dry under reduced pressure, or even under vacuum, using a vacuum pump or the like.
  • the temperature conditions for drying should be at or above the boiling point of the protic organic solvent used, and of the solvent used as necessary. As this can vary depending on the type of protic organic solvent and solvent used, it is not possible to give a general statement regarding specific temperature conditions, but it is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher, with the upper limit being preferably less than 130°C, more preferably 125°C or lower, and even more preferably 120°C or lower.
  • the pressure is preferably 85 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa or less, and the lower limit may be a vacuum (0 kPa).
  • the pressure is preferably 1 kPa or more, more preferably 2 kPa or more, and even more preferably 3 kPa or more.
  • 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 the above-mentioned further heating is not performed, an amorphous sulfide solid electrolyte is obtained, and if heating is performed, a crystalline sulfide solid electrolyte is obtained.
  • the amorphous sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and representative examples thereof include solid electrolytes such as Li 2 S-P 2 S 5 -Li 2 O and Li 2 S-P 2 S 5 -P 2 O 5 .
  • the types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by the types and amounts of raw materials used, or by an ICP emission spectrometer.
  • the shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, a particulate shape.
  • the average particle size ( D50 ) 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, or 0.1 ⁇ m or more, and the upper limit is 200.0 ⁇ m or less, further 100.0 ⁇ m or less, 10.0 ⁇ m or less, 1.0 ⁇ m or less, or 0.5 ⁇ m or less.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and oxygen atoms, and may be a so-called glass ceramic obtained by heating an amorphous sulfide solid electrolyte (glass) to a crystallization temperature or higher.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment can be any one having a crystal structure composed of lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms, without any particular limitation.
  • a crystalline sulfide solid electrolyte having a LGPS type crystal structure represented by Li3 + xPS4 - yOy (x satisfies -1 ⁇ x ⁇ 1, and y satisfies 0 ⁇ y ⁇ 4) also referred to as "Li-P-S-O-based sulfide solid electrolyte" is preferred because of its high ionic conductivity.
  • x is preferably -0.7 or more, more preferably -0.3 or more, even more preferably -0.1 or more, even more preferably 0.0 or more, and particularly preferably 0.2 or more, with an upper limit of preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.7 or less.
  • y is preferably 0.5 or more, more preferably 0.8 or more, even more preferably 1.0 or more, and even more preferably 1.3 or more, with an upper limit of preferably 3.5 or less, more preferably 3.0 or less, even more preferably 2.5 or less, and even more preferably 2.0 or less.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned LGPS type crystal structure or may contain it as a main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferable that it contains it as a main crystal.
  • "containing it as a main crystal” means that the ratio of the target crystal structure among the crystal structures is 80% or more, preferably 90% or more, and more preferably 95% or more.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably one that does not contain crystalline Li 3 PS 4 ( ⁇ -Li 3 PS 4 ).
  • the mole numbers M L , L P , and M S of these atoms have the following relationship.
  • the ratio (M S /M P ) of the number of moles of sulfur atoms (M S ) to the number of moles of phosphorus atoms (M P ) is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and still more preferably 2.0 or more, and the upper limit is preferably 4.0 or less, more preferably 3.5 or less, even more preferably 3.2 or less, and still more preferably 2.7 or less.
  • the ratio ( ML / MP ) of the number of moles of lithium atoms ( ML ) to the number of moles of phosphorus atoms ( MP ) is preferably 2.3 or more, more preferably 2.7 or more, even more preferably 2.9 or more, still more preferably 3.0 or more, and particularly preferably 3.2 or more, and the upper limit is preferably 3.9 or less, more preferably 3.8 or less, even more preferably 3.7 or less, and still more preferably 3.6 or less.
  • the ratio (M S /M P ) and the ratio ( ML /M P ) are within the above-mentioned numerical ranges, the LGPS-type crystal structure and other crystal structures are easily formed, and as a result, excellent ionic conductivity, water resistance, and electrochemical stability are easily obtained.
  • the sulfide solid electrolyte obtained by the manufacturing method of the present embodiment may further contain carbon atoms in addition to lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms.
  • the carbon atoms are mainly due to carbon atoms contained in the protic organic solvent containing oxygen atoms.
  • the content of carbon atoms in the sulfide solid electrolyte is about 0.1% by mass or more and 10% by mass or less.
  • the value of 2 ⁇ in the diffraction peak of the LGPS type crystal structure may vary within a range of ⁇ 0.4°, and may further vary within a range of ⁇ 0.3° and ⁇ 0.1°.
  • the value of 2 ⁇ related to the LGPS type crystal structure is assumed to vary within a range of ⁇ 0.4°, further ⁇ 0.3°, and ⁇ 0.1°, unless otherwise specified.
  • the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment has the above-mentioned LGPS-type crystal structure, it also has another crystal structure.
  • the diffraction peak of the other crystal structure appears at least near 26.4°. It may also appear near 16.7°, 30.0°, and 33.9°.
  • the value of 2 ⁇ may vary within a range of ⁇ 0.5°, and may also vary within a range of ⁇ 0.3° or ⁇ 0.1°.
  • the value of 2 ⁇ for crystal structures other than the LGPS-type crystal structure is assumed to vary within a range of ⁇ 0.5°, and further ⁇ 0.3° or ⁇ 0.1°, unless otherwise specified.
  • the half-width is preferably 1.5° or less, more preferably 1.4° or less, and even more preferably 1.3° or less, with the lower limit being the smaller the better, and although there is no particular restriction, it is usually 0.4° or more. If the half-width is small within the above range, the crystallite diameter becomes large and the crystal structure becomes more excellent, improving ionic conductivity as well as water resistance and electrochemical stability.
  • the sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably one in which a peak due to PSO 3 3- is observed at 34.0 ⁇ 5.0 ppm by solid-state 31 P-NMR measurement, and more preferably one in which a peak due to PO 4 3- is observed at 6.0 ⁇ 5.0 ppm, and further preferably one in which a peak due to PS 2 O 2 3- is observed at 67.0 ⁇ 5.0 ppm.
  • the peak due to PSO 3 3 ⁇ , the peak due to PO 4 3 ⁇ , and the peak due to PS 2 O 2 3 ⁇ indicate that at least the sulfide solid electrolyte obtained by the production method of this embodiment has oxygen in its structure.
  • the shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, a particulate shape.
  • the average particle size ( D50 ) 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, or 0.1 ⁇ m or more, and the upper limit is 200.0 ⁇ m or less, further 100.0 ⁇ m or less, 10.0 ⁇ m or less, 8.0 ⁇ m or less, 6.0 ⁇ m or less, 5.0 ⁇ m or less, 3.0 ⁇ m or less, 1.0 ⁇ m or less, or 0.5 ⁇ m or less.
  • the method for producing the sulfide solid electrolyte of this embodiment there are no particular limitations on the method for producing the sulfide solid electrolyte of this embodiment, but as described above, it is preferable to produce it by the method for producing the sulfide solid electrolyte of this embodiment. Therefore, the properties of the sulfide solid electrolyte of this embodiment are the same as those described above as the properties of the sulfide solid electrolyte obtained by the method for producing the sulfide solid electrolyte of this embodiment.
  • the sulfide solid electrolyte of this embodiment (including the sulfide solid electrolyte obtained by the manufacturing method of this embodiment) has excellent water resistance.
  • the amount of hydrogen sulfide generated is 1.5 cm 3 /g-sample or less, further 1.3 cm 3 /g-sample or less, 1.0 cm 3 / g-sample or less, 0.8 cm 3 /g-sample or less, and 0.7 cm 3 /g-sample or less.
  • the sulfide solid electrolyte of this embodiment can suppress the amount of hydrogen sulfide generated even when it comes into contact with moisture (e.g., moisture in the air) during, for example, battery production, and has excellent water resistance.
  • the sulfide solid electrolyte obtained by the production method of this embodiment has high ionic conductivity and excellent battery performance, and is therefore suitable for use in batteries, particularly lithium ion batteries, and particularly all-solid-state batteries.
  • the sulfide solid electrolyte of the present embodiment may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer. Each layer may be manufactured by a known method.
  • the battery uses 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 of a material that reacts with the solid electrolyte such as Au, Pt, Al, Ti, or Cu, coated with Au or the like can be used.
  • Powder X-ray diffraction (XRD) measurements were carried out as follows.
  • the sulfide solid electrolyte powder obtained in the examples and comparative examples was filled into a groove (diameter: 18 mm, depth: 0.5 mm) of a sample table, leveled with glass, and a small amount of standard silicon (standard sample for X-ray diffraction, manufactured by NIST) was sprinkled on the surface to prepare a sample.
  • This sample was sealed in a general-purpose atmosphere separator (manufactured by Rigaku Corporation) and measured under the following conditions without exposing it to air.
  • Measuring device Miniflex 600, manufactured by Rigaku Corporation Tube voltage: 40 kV Tube current: 15mA
  • X-ray wavelength Cu-K ⁇ radiation (1.5418 ⁇ )
  • Optical system focusing method Slit configuration: incident solar slit 2.5°, receiving solar slit 2.5°, IHS: 10.0 mm, DS: 1.25 deg, SS: 13 mm (open), RS: 13.0 mm, K ⁇ filter (Ni plate) used
  • the half-width of the peak obtained by the powder XRD diffraction measurement was obtained as follows. That is, a straight line baseline was set on the peak shape obtained by the XRD measurement, and the difference between the intensity at each point and the baseline was taken to obtain an XRD curve (see FIG. 16).
  • the ionic conductivity was measured as follows. From the crystalline solid electrolytes obtained in the Examples and Comparative Examples, 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 to prepare samples. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C by an AC impedance method (frequency range: 7 MHz to 0.1 Hz, amplitude: 100 mV) to obtain a Cole-Cole plot.
  • AC impedance method frequency range: 7 MHz to 0.1 Hz, amplitude: 100 mV
  • Peak separation When peak separation is performed, the obtained solid-state 31P -NMR spectrum is analyzed using the software "FT-NMR" (software included in “Data Processing of FT-NMR Using a Personal Computer”, Revised Edition (Second Edition) (Sankyo Publishing)) to determine the separated peaks.
  • the above software calculates the separated peaks, the calculated NMR signal values, and the residual sum of squares R2 from the NMR signals (experimental values) using the nonlinear least squares method. Peak separation is considered complete when the residual sum of squares R2 within the analysis range between the experimental values and the calculated values when the maximum peak height is 1 is 0.007 or less and the number of separated peaks is the smallest.
  • CV Measurement 1 In order to evaluate the electrochemical stability during oxidation and reduction, CV measurement was performed using the following CV measurement cell. In a glove box in an Ar atmosphere, 120 mg of the solid electrolyte obtained in Example 11 was weighed, placed in a battery cell with a diameter of 10 mm, and pressed and molded at 360 MPa with a SUS mold. One side of the mold was removed, and an In/Li alloy foil made by bonding an In foil (10 mm ⁇ , thickness: 0.3 mm) and a Li foil (8 mm ⁇ , thickness: 0.25 mm) was placed in, and the mold was returned, and then pressed again at 120 MPa and fixed with four screws sandwiching an insulator to obtain a measurement cell.
  • the measurement cell obtained by the above method was connected to a measurement device (Solartron, SI-1287) and a CV curve was obtained under the following conditions.
  • Example 1 In a Schlenk flask (volume: 100 mL) containing a stirrer, 20 mL of ethanol (EtOH), a protic organic solvent containing oxygen atoms, was added under a nitrogen atmosphere, and the stirrer was rotated. Then, 0.552 g of lithium sulfide was introduced and stirring was continued for 5 minutes, and then 0.890 g of diphosphorus pentasulfide was introduced and stirring was continued for 5 minutes to prepare a solution. The resulting solution was dried at 120° C. under vacuum to obtain a powder solute (amorphous sulfide solid electrolyte). The resulting powder solute was heated at 400° C.
  • EtOH ethanol
  • the obtained crystalline sulfide solid electrolyte was subjected to powder XRD diffraction measurement.
  • the X-ray diffraction pattern is shown in FIG. 1. The ionic conductivity was measured and found to be 2.8 ⁇ 10 ⁇ 5 (S/cm).
  • Example 2 0.552 g of lithium sulfide and 0.890 g of diphosphorus pentasulfide were mixed in a mortar for 5 minutes, and the mixed raw materials were introduced into a Schlenk flask (volume: 100 mL) with a stirrer under a nitrogen atmosphere. After rotating the stirrer, 20 mL of ethanol (EtOH), a protic organic solvent containing oxygen atoms, was added and stirred for 5 minutes to prepare a solution. The resulting solution was dried at 120 ° C. under vacuum to obtain a powder solute (amorphous sulfide solid electrolyte). The obtained powder solute was heated at 400 ° C.
  • EtOH ethanol
  • the obtained crystalline sulfide solid electrolyte was subjected to powder XRD diffraction measurement.
  • the X-ray diffraction pattern is shown in FIG. 2.
  • the ionic conductivity was measured and found to be 2.8 ⁇ 10 ⁇ 5 (S/cm).
  • Examples 3, 6, 8 and 10 A crystalline sulfide solid electrolyte powder was obtained in the same manner as in Example 1, except that lithium sulfide and diphosphorus pentasulfide were used in amounts in a ratio shown in Table 1 and the protic organic solvent was changed to a solvent shown in Table 1.
  • the obtained crystalline sulfide solid electrolyte was subjected to powder XRD diffraction measurement.
  • the X-ray diffraction patterns are shown in Figures 3, 6, 8 and 10, respectively.
  • the results of measuring the ionic conductivity are shown in Table 1.
  • Example 2 lithium sulfide and diphosphorus pentasulfide were used in amounts in a ratio shown in Table 1, and the protic organic solvent and heating conditions (heating temperature and heating time) were changed to those shown in Table 1.
  • the same procedure as in Example 2 was repeated to obtain a crystalline sulfide solid electrolyte powder, except that the amounts of lithium sulfide and diphosphorus pentasulfide used were changed to those shown in Table 1.
  • the obtained crystalline sulfide solid electrolyte was subjected to powder XRD diffraction measurement.
  • the X-ray diffraction patterns are shown in Figures 4, 5, 7, 9, and 11 to 13, respectively.
  • the results of measuring the ionic conductivity are shown in Table 1.
  • CV measurement was performed based on the above method, and the results are shown in Figure 19.
  • Example 1 The same procedure as in Example 1 was carried out except that ethanol was replaced with toluene, an aprotic solvent, in place of ethanol in Example 1. Instead of a solution, a slurry-like fluid was obtained. The slurry-like fluid was dried at 120° C. under vacuum to obtain a powder. The X-ray diffraction pattern is shown in FIG. 14. In the aprotic solvent, the reaction of the raw materials did not proceed, and peaks of Li 2 S and P 2 S 5 were confirmed. The powder was then heated at 400°C for 2 hours in an electric furnace to obtain a powder. The powder was subjected to powder XRD diffraction measurement. The X-ray diffraction pattern is shown in Figure 15. The results of measuring the ionic conductivity are shown in Table 2. It was found that Li4P2S6 crystals and a small amount of ⁇ - Li3PS4 crystals appeared upon heating , and the conductivity was also low.
  • Comparative Examples 2 and 3 Example 1 and Comparative Example 1 described in JP 2019-192490 A are referred to as Comparative Examples 2 and 3 in this specification, respectively.
  • Table 2 The results of determining the half-width and intensity of the XRD peak together with the composition and manufacturing conditions described in the publication are shown in Table 2.
  • the results are shown in Table 1.
  • Solid-state 31 P-NMR measurements were carried out on the powders of Examples 4 and 9.
  • the solid-state 31 P-NMR spectra are shown in FIG.
  • the phosphorus ratio (mol%) contained in each structure was calculated based on the peak area attributable to each structure.
  • the phosphorus ratio (mol%) contained in each structure was calculated from the ratio of the peak area of each structure to the total area of the peaks attributable to each structure shown in Table 3.
  • the calculated phosphorus ratios (mol%) of each structure are shown in Table 3.
  • the mixing method "(1)” indicates that lithium sulfide is mixed with an organic solvent, and then phosphorus sulfide is added and mixed (the above mixing method (1)), while “(2)” indicates that all the raw material ingredients are mixed with an organic solvent (the above mixing method (2)). Also, “quenching” indicates the melt quenching method.
  • the crystalline sulfide solid electrolytes of Examples 4 and 9 were observed to have a peak due to PSO 3 3- (34.0 ⁇ 5.0 ppm), a peak due to PO 4 3- (6.0 ⁇ 5.0 ppm), and a peak due to PS 2 O 2 3- (67.0 ⁇ 5.0 ppm), and it was confirmed that they had oxygen atoms in their crystal structures.
  • the sulfide solid electrolyte of this embodiment did not show any deterioration behavior over a wide potential range of -1.12 to 5.0 V, and it was confirmed that it is an electrochemically stable material.
  • the powder obtained by mixing the raw material contents with the protic organic solvent to prepare a solution was a sulfide solid electrolyte having an LGPS-type crystal structure containing oxygen atoms, even though no raw material containing oxygen atoms was used as the raw material contents.
  • the oxygen atoms of the protic organic solvent containing oxygen atoms were incorporated into the sulfide solid electrolyte and were incorporated as atoms that constitute the crystal structure.
  • a sulfide solid electrolyte having an LGPS-type crystal structure could be obtained at a low temperature of 300 to 400°C, whereas a high temperature of 700 to 950°C was previously required.
  • Example 14 Using the sample obtained in Example 11, the following CV measurement and hydrogen sulfide generation test were carried out.
  • the measurement cell was sealed in a sealed container using a separable flask, and CV measurement (3 cycles) was performed under the following conditions:
  • the measurement instrument used was the same as that used in CV measurement 1 above (manufactured by Solartron, SI-1287).
  • CV measurement 2 is a method performed under harsher conditions that are more prone to reduction than CV measurement 1, since it uses metallic Li foil.
  • the results in Figure 20 confirm that even under such harsh conditions, degradation behavior is suppressed, and that it is an electrochemically stable material.
  • the amount of hydrogen sulfide generated in 3 hours was 0.5 cm 3 /g-sample.
  • the amount of hydrogen sulfide generated was 1.6 cm 3 /g-sample. From these results, it was confirmed that the method for producing a sulfide solid electrolyte of this embodiment can provide a sulfide solid electrolyte having excellent water resistance and suppressing the amount of hydrogen sulfide generated.
  • a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, and oxygen atoms can be produced with high production efficiency.
  • a liquid phase method is adopted in which a solution is prepared by mixing raw material contents with a protic organic solvent, it is easy to respond to increases and decreases in scale, and it is easy to respond to mass production.
  • the sulfide solid electrolyte of this embodiment obtained by the production method of this embodiment is suitable for use as a battery, particularly a lithium ion battery, particularly an all-solid-state battery, in information-related devices and communication devices such as personal computers, video cameras, and mobile phones. It is suitable for use as a battery.

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Abstract

Sont proposés : un procédé de production d'électrolyte solide au sulfure qui fournit, à une efficacité de production élevée, un électrolyte solide au sulfure qui contient des atomes de lithium, des atomes de phosphore, des atomes de soufre et des atomes d'oxygène, et qui présente une résistance à l'eau élevée, le procédé consistant à mélanger une substance contenant une matière première et un solvant organique protonique contenant des atomes d'oxygène pour ainsi préparer une solution ; et un électrolyte solide au sulfure qui contient des atomes de lithium, des atomes de phosphore, des atomes de soufre et des atomes d'oxygène, et qui présente un pic de diffraction prescrit dans une mesure de diffraction par rayons X à l'aide d'un rayon CuKα.
PCT/JP2023/043372 2022-12-05 2023-12-05 Électrolyte solide au sulfure et procédé de production d'électrolyte solide au sulfure WO2024122518A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019207956A1 (fr) * 2018-04-25 2019-10-31 国立大学法人東京工業大学 Électrolyte solide au sulfure et batterie entièrement solide
JP2020027781A (ja) * 2018-08-16 2020-02-20 三菱瓦斯化学株式会社 Ｌｇｐｓ系固体電解質の製造方法
WO2021054220A1 (fr) * 2019-09-17 2021-03-25 出光興産株式会社 Procédé de production d'électrolyte solide, et précurseur d'électrolyte

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019207956A1 (fr) * 2018-04-25 2019-10-31 国立大学法人東京工業大学 Électrolyte solide au sulfure et batterie entièrement solide
JP2020027781A (ja) * 2018-08-16 2020-02-20 三菱瓦斯化学株式会社 Ｌｇｐｓ系固体電解質の製造方法
WO2021054220A1 (fr) * 2019-09-17 2021-03-25 出光興産株式会社 Procédé de production d'électrolyte solide, et précurseur d'électrolyte

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