WO2025013675A1 - 硫化物固体電解質の製造方法および再利用方法 - Google Patents

硫化物固体電解質の製造方法および再利用方法 Download PDF

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WO2025013675A1
WO2025013675A1 PCT/JP2024/023754 JP2024023754W WO2025013675A1 WO 2025013675 A1 WO2025013675 A1 WO 2025013675A1 JP 2024023754 W JP2024023754 W JP 2024023754W WO 2025013675 A1 WO2025013675 A1 WO 2025013675A1
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solid electrolyte
sulfide solid
melt
carbon
sulfide
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French (fr)
Japanese (ja)
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秀悦 関
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AGC Inc
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Asahi Glass Co Ltd
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Priority to KR1020267000206A priority Critical patent/KR20260035189A/ko
Priority to JP2025532690A priority patent/JPWO2025013675A1/ja
Publication of WO2025013675A1 publication Critical patent/WO2025013675A1/ja
Priority to US19/428,502 priority patent/US20260112692A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/54—Reclaiming serviceable parts of waste accumulators
    • 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
    • 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 and reusing a sulfide solid electrolyte.
  • Lithium ion secondary batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Traditionally, liquid electrolytes have been used in lithium ion secondary batteries. However, in recent years, all-solid-state lithium ion secondary batteries that use solid electrolytes as the electrolyte have been attracting attention because of the promise of improved safety, high-speed charging and discharging, and smaller cases.
  • An example of a solid electrolyte used in all-solid-state lithium ion secondary batteries is a sulfide solid electrolyte.
  • Patent Document 1 discloses a method for eliminating the deviation in composition by contacting a sulfide solid electrolyte having a deviation in composition with an alkali metal sulfide or the like by a solid-phase method. In addition to cases where composition deviation does not occur, there is a demand for reusing a sulfide solid electrolyte that has been obtained to separately produce a new sulfide solid electrolyte.
  • the solid-phase method when using the solid-phase method to recycle the sulfide solid electrolyte and produce a new sulfide solid electrolyte, there are problems in that the solid-phase reaction takes a long time and it is difficult to obtain a sulfide solid electrolyte with a homogeneous composition.
  • the solid-phase method is a process that is easily affected by the particle size of the original electrolyte to be reused, making it difficult to control the particle size to be newly obtained. Therefore, although it is possible to recover the lithium ion conductivity, it is difficult to reuse the electrolyte if the particle size is outside the specifications.
  • a dry reaction there is also the problem that residual solvent adheres to the electrolyte and causes reaction inhibition.
  • the present invention aims to provide a method for producing a new sulfide solid electrolyte using a sulfide solid electrolyte.
  • the present inventors have focused on a method for reusing sulfide solid electrolytes by a melting method.
  • the melting method can shorten the reaction time compared to the solid-phase method, and also makes it easier to obtain sulfide solid electrolytes with a homogeneous composition.
  • the sulfide solid electrolyte is first melted, there is no problem with particle size control as occurs in the solid-phase method.
  • carbon derived from the solvent used in the wet grinding remains in the electrolyte, and this carbon is converted to inorganic carbon (elemental carbon) when melted.
  • the present invention relates to a method for producing a sulfide solid electrolyte, which includes heating and melting a wet-ground first sulfide solid electrolyte to obtain a molten liquid, removing carbon from the molten liquid, and cooling the molten liquid from which the carbon has been removed to obtain a second sulfide solid electrolyte.
  • a sulfide solid electrolyte with excellent lithium ion conductivity can be produced by a melting method using a sulfide solid electrolyte.
  • FIG. 1 is a flowchart of a method for producing a sulfide solid electrolyte according to an embodiment of the present invention.
  • FIG. 2 is a diagram showing the results of AC impedance measurement in the examples.
  • a method for producing a sulfide solid electrolyte according to an embodiment of the present invention (hereinafter also referred to as the present production method) is characterized in that it includes heating and melting a wet-pulverized first sulfide solid electrolyte to obtain a melt, removing carbon from the melt, and cooling the melt from which the carbon has been removed to obtain a second sulfide solid electrolyte.
  • Figure 1 shows a flowchart of this manufacturing method.
  • the wet-ground first sulfide solid electrolyte is heated and melted to obtain a molten liquid
  • carbon is removed from the molten liquid (step S1)
  • the molten liquid from which the carbon has been removed is cooled to obtain a second sulfide solid electrolyte (step S2).
  • a wet-pulverized first sulfide solid electrolyte (hereinafter, also simply referred to as the first sulfide solid electrolyte) is used.
  • carbon derived from the solvent used in the wet-pulverization remains in the first sulfide solid electrolyte. Therefore, such carbon as an organic component changes to inorganic carbon when melted, and the resulting electrolyte exhibits electronic conductivity. Therefore, in the present invention, a process of removing carbon from the melt is performed to suppress the expression of electronic conductivity caused by inorganic carbon, and a sulfide solid electrolyte with excellent lithium ion conductivity is manufactured.
  • Sulfide solid electrolyte raw material As the first sulfide solid electrolyte, a commercially available sulfide solid electrolyte may be used, or one produced from a sulfide solid electrolyte raw material may be used. A solid electrolyte raw material may be used, or a sulfide solid electrolyte raw material produced from a material may be used. In addition, the sulfide solid electrolyte raw material may be subjected to a conventionally known pretreatment.
  • the sulfide solid electrolyte raw material will be specifically described below.
  • the sulfide solid electrolyte raw material usually contains an alkali metal element (R) and a sulfur element (S).
  • the alkali metal element (R) examples include lithium element (Li), sodium element (Na), and potassium element (K), with lithium element (Li) being preferred.
  • the source of the alkali metal element (R) an appropriate combination of substances (components) containing an alkali metal element, such as an alkali metal element alone or a compound containing an alkali metal element, can be used.
  • the lithium element an appropriate combination of substances (components) containing Li, such as Li alone or a compound containing Li, can be used.
  • Examples of the substance containing lithium element (Li) include lithium compounds such as lithium sulfide ( Li2S ), lithium iodide (LiI), lithium carbonate ( Li2CO3 ), lithium sulfate ( Li2SO4 ), lithium oxide ( Li2O ), and lithium hydroxide (LiOH), as well as metallic lithium, etc. From the viewpoint of obtaining a sulfide material, it is preferable to use lithium sulfide as the substance containing lithium element (Li).
  • S sulfur
  • substances (components) containing S such as simple S or compounds containing S
  • One type of substance containing sulfur (S) can be used, or two or more types can be used in combination.
  • Examples of substances containing sulfur element (S) include phosphorus sulfide such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ), other sulfur compounds containing phosphorus, elemental sulfur, and compounds containing sulfur.
  • Examples of compounds containing sulfur include H 2 S, CS 2 , iron sulfide (FeS, Fe 2 S 3 , FeS 2 , Fe 1-x S, etc.), bismuth sulfide (Bi 2 S 3 ), and copper sulfide (CuS, Cu 2 S, Cu 1-x S, etc.).
  • the substance containing sulfur element (S) is preferably phosphorus sulfide, and more preferably diphosphorus pentasulfide (P 2 S 5 ). These may be used alone or in combination of two or more. Phosphorus sulfide can be considered as a compound that serves both as a substance containing S and a substance containing P described later.
  • the sulfide solid electrolyte raw material preferably further contains phosphorus (P) from the viewpoint of improving the ionic conductivity of the resulting sulfide solid electrolyte.
  • P phosphorus
  • a suitable combination of P-containing substances (components), such as simple P or compounds containing P, can be used.
  • substances containing phosphorus element (P) include phosphorus sulfides such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ), phosphorus compounds such as sodium phosphate (Na 3 PO 4 ), and elemental phosphorus.
  • the substance containing phosphorus element (P) is preferably phosphorus sulfide having high volatility, and more preferably diphosphorus pentasulfide (P 2 S 5 ). These may be used alone or in combination of two or more.
  • the sulfide solid electrolyte raw material may be obtained as a mixed raw material by, for example, appropriately mixing the above-mentioned substances according to the composition of the desired sulfide solid electrolyte.
  • the mixing ratio is not particularly limited, but for example, the molar ratio S/R of the sulfur element (S) to the alkali metal element (R) in the sulfide solid electrolyte raw material is preferably 0.65/0.35 or less, and more preferably 0.5/0.5 or less, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte.
  • An example of a preferred combination of an alkali metal element and a sulfur element contained in the sulfide solid electrolyte raw material is a combination of Li 2 S and P 2 S 5.
  • the molar ratio Li/P of Li and P is preferably 40/60 or more, more preferably 50/50 or more.
  • the molar ratio Li/P of Li and P is preferably 88/12 or less.
  • the molar ratio Li/P of Li and P is preferably 40/60 to 88/12, more preferably 50/50 to 88/12.
  • the sulfide solid electrolyte raw material preferably contains, as a substance containing Li, one or more selected from the group consisting of metallic lithium, lithium iodide (LiI), lithium carbonate (Li 2 CO 3 ), lithium sulfate (Li 2 SO 4 ), lithium oxide (Li 2 O), and lithium hydroxide (LiOH). These may be used alone or in combination of two or more.
  • the sulfide solid electrolyte raw material may contain further substances (compounds, etc.) in addition to the above substances depending on the composition of the desired sulfide solid electrolyte or as additives, etc.
  • the sulfide solid electrolyte raw material when producing a sulfide solid electrolyte containing a halogen element such as F, Cl, Br or I, the sulfide solid electrolyte raw material preferably contains a halogen element (Ha).
  • the sulfide solid electrolyte raw material preferably contains a compound containing a halogen element.
  • compounds containing a halogen element include lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, and boron halides.
  • lithium halides are preferred as compounds containing a halogen element, and LiCl, LiBr, and LiI are more preferred. These may be used alone or in combination of two or more.
  • an alkali metal halide such as lithium halide is also a compound containing an alkali metal element such as Li.
  • the sulfide solid electrolyte raw material contains an alkali metal halide, some or all of the alkali metal element such as Li in the sulfide solid electrolyte raw material may be derived from an alkali metal halide such as lithium halide.
  • the molar equivalent of Ha relative to P in the sulfide solid electrolyte raw material is preferably 0.2 molar equivalents or more, and more preferably 0.5 molar equivalents or more, from the viewpoint of improving the ionic conductivity of the resulting sulfide solid electrolyte.
  • the molar equivalent of Ha is preferably 4 molar equivalents or less, and more preferably 3 molar equivalents or less.
  • the obtained sulfide solid electrolyte may be an amorphous sulfide solid electrolyte depending on the purpose, and from the viewpoint of improving the ease of generating an amorphous phase, it is also preferable that the sulfide solid electrolyte raw material contains a sulfide such as SiS 2 , B 2 S 3 , GeS 2 , or Al 2 S 3.
  • a sulfide such as SiS 2 , B 2 S 3 , GeS 2 , or Al 2 S 3.
  • oxides such as SiO 2 , B 2 O 3 , GeO 2 , Al 2 O 3 , and P 2 O 5. These may be used alone or in combination of two or more.
  • Solid-phase method, melting method examples of methods for producing the first sulfide solid electrolyte using the sulfide solid electrolyte raw material include a method using a solid phase method and a method using a melting method. Hereinafter, the method using the solid phase method and the method using the melting method will be described separately.
  • Solid Phase Method In the solid-phase method, first, the sulfide solid electrolyte raw materials are mixed.
  • a conventionally known method can be used for mixing, mixing by mechanical milling is preferable.
  • examples of the milling include a rotary ball mill that imparts rotational motion to a container, a vibration ball mill that imparts vibrational motion, a planetary ball mill that imparts revolution and rotational motion, a bead mill, and an Attritor (registered trademark).
  • a planetary ball mill and a bead mill which have a higher mixing power and pulverizing power, are preferable.
  • the ball mill may be used for dry mixing or wet mixing using a dispersion medium, but from the viewpoint of efficient energy transfer, dry mixing is preferred.
  • the raw materials are mixed by the above mixing to form a raw material mixture.
  • This raw material mixture becomes a precursor of the sulfide solid electrolyte.
  • the precursor may be a homogeneous amorphous intermediate compound that has been made amorphous by adopting much stricter mixing conditions than conventionally.
  • An amorphous intermediate compound means that no XRD peaks derived from the raw materials are observed.
  • the raw material mixture is wet-pulverized to form the first sulfide solid electrolyte.
  • the wet pulverization may be performed together with the mixing (wet mixing) of the sulfide solid electrolyte raw materials described above.
  • Wet pulverization is performed in a solvent using a media made of alumina, zirconia, or a bead mill, and methods conventionally known in this field can be used.
  • a solvent containing carbon is used, and examples of the solvent include alkanes such as heptane, hexane, and octane, aromatic hydrocarbons such as benzene, toluene, and xylene, and ether compounds having 2 to 20 carbon atoms such as diethyl ether, dibutyl ether, and anisole.
  • alkanes such as heptane, hexane, and octane
  • aromatic hydrocarbons such as benzene, toluene, and xylene
  • ether compounds having 2 to 20 carbon atoms such as diethyl ether, dibutyl ether, and anisole.
  • the average particle size of the sulfide solid electrolyte after grinding is 1 to 100 ⁇ m.
  • the average particle size refers to the median diameter (D50), which is the particle size at which 50 volume percent of the particles are equal to or smaller than this value, and is determined from the volume-based particle size distribution chart obtained by measuring the particle size distribution using a particle size distribution analyzer using the laser diffraction method.
  • the sulfide solid electrolyte raw materials are first mixed to obtain a raw material mixture.
  • the mixing may be performed, for example, by mixing in a mortar, mixing using a media such as a planetary ball mill, or media-less mixing such as a pin mill, a powder mixer, or airflow mixing.
  • the raw material mixture obtained above is heated to obtain a melt.
  • the specific method of heating and melting the raw material mixture is not particularly limited, and for example, the raw material mixture is placed in a heat-resistant container and heated in a heating furnace.
  • the raw material mixture may be sealed in a heat-resistant container.
  • Melting may also be performed in an atmosphere containing elemental sulfur.
  • the atmosphere containing elemental sulfur may be a mixed gas atmosphere of a gas containing elemental sulfur, such as sulfur gas, hydrogen sulfide gas, or sulfur dioxide gas, and an inert gas.
  • the heat-resistant container may be a heat-resistant container made of carbon, a heat-resistant container containing an oxide such as quartz, quartz glass, borosilicate glass, aluminosilicate glass, alumina, zirconia, or mullite, a heat-resistant container containing a nitride such as silicon nitride or boron nitride, or a heat-resistant container containing a carbide such as silicon carbide.
  • these heat-resistant containers may be made of the above-mentioned materials in bulk, or may be a container on which a layer of carbon, oxide, nitride, or carbide is formed, such as a carbon-coated quartz tube.
  • the heating temperature when the raw material mixture is heated and melted varies depending on the raw materials used and the composition of the raw material mixture, but is preferably 550 to 1000°C, more preferably 600 to 950°C, even more preferably 630 to 900°C, and particularly preferably 650 to 800°C.
  • the heating temperature is preferably 550°C or higher, more preferably 600°C or higher, even more preferably 630°C or higher, and particularly preferably 650°C or higher, from the viewpoint of increasing the meltability of the raw materials and homogenizing the molten liquid in a short time.
  • the heating temperature is preferably 1000°C or lower, more preferably 950°C or lower, even more preferably 900°C or lower, and particularly preferably 800°C or lower, from the viewpoint of suppressing deterioration of the components due to heating, suppressing compositional deviation due to volatilization of the components, and further suppressing decomposition.
  • the heat melting time varies depending on the scale, but is preferably 10 minutes to 10 hours, more preferably 30 minutes to 9.5 hours, even more preferably 45 minutes to 9 hours, and particularly preferably 1 to 9 hours. From the viewpoint of smoothly progressing the reaction, the heat melting time is preferably 10 minutes or more, more preferably 30 minutes or more, even more preferably 45 minutes or more, and particularly preferably 1 hour or more. Also, from the viewpoint of productivity, the heat melting time is preferably 10 hours or less, more preferably 9.5 hours or less, and even more preferably 9 hours or less.
  • the pressure during the heating and melting is not particularly limited, but for example, normal pressure or slight pressure is preferable, and normal pressure is more preferable.
  • the dew point during heat melting is preferably ⁇ 20° C. or lower, and although there is no particular lower limit, it is usually about ⁇ 80° C.
  • the oxygen concentration is preferably 1000 ppm by volume or lower. The complete dissolution of the molten material can be confirmed by the absence of peaks derived from crystals in high-temperature X-ray diffraction measurement.
  • the cooling can be performed by any known method, and there are no particular limitations on the method used; however, in order to increase the cooling rate, it is preferable to use twin rollers, which are generally considered to have the fastest quenching speed.
  • the cooling rate is preferably 0.01°C/sec or more, more preferably 0.05°C/sec or more, and even more preferably 0.1°C/sec or more.
  • the cooling rate of the twin rollers is, for example, 1,000,000°C/sec or less.
  • the cooling rate when rapidly cooling is preferably 10°C/sec or more, more preferably 100°C/sec or more, even more preferably 500°C/sec or more, and particularly preferably 700°C/sec or more.
  • the cooling rate of the twin rollers is, for example, 1,000,000°C/sec or less.
  • the solid may be slowly cooled during the cooling step to crystallize at least a portion of the solid, to obtain a sulfide solid electrolyte having a specific crystal structure or a sulfide solid electrolyte composed of a crystalline phase and an amorphous phase.
  • the cooling rate in the case of slowly cooling is preferably 0.01 ° C./sec or more, more preferably 0.05 ° C./sec or more.
  • the cooling rate is preferably 500 ° C./sec or less, more preferably 450 ° C./sec or less.
  • the cooling rate may be 10 ° C./sec or less, or 5 ° C./sec or less.
  • the cooling rate may be appropriately adjusted depending on the crystallization conditions.
  • the sulfide solid electrolyte crystal is preferably an ion-conductive crystal, specifically, a crystal having a lithium ion conductivity of more than 1.0 ⁇ 10 ⁇ 4 S/cm, more preferably more than 1.0 ⁇ 10 ⁇ 3 S/cm.
  • the solid obtained after cooling is a sulfide solid electrolyte containing a crystalline phase
  • a compound that will become a crystal nucleus in the melt but examples include adding a compound that will become a crystal nucleus to a raw material or intermediate, or adding a compound that will become a crystal nucleus to the melt during heat-melting.
  • Compounds that can become crystal nuclei include oxides, oxynitrides, nitrides, carbides, other chalcogen compounds, halides, etc.
  • Compounds that can become crystal nuclei are preferably compounds that have a certain degree of compatibility with the melt. Compounds that are completely incompatible with the melt cannot become crystal nuclei.
  • the content of the compound that will become the crystal nucleus in the melt is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 1 mass% or more.
  • the content of the compound that will become the crystal nucleus in the melt is preferably 20 mass% or less, and more preferably 10 mass% or less.
  • the melt does not contain compounds that will become crystal nuclei, or that the content of such compounds is less than a specified amount.
  • the content of compounds that will become crystal nuclei in the melt is preferably 1 mass% or less, and more preferably 0.1 mass% or less.
  • the content of compounds that will become crystal nuclei in the melt may be 0.01 mass% or less.
  • the cooling is preferably carried out under normal pressure.
  • Under normal pressure means that the pressure is not controlled during cooling. Specifically, it is about 0.8 to 1.2 atm.
  • the raw material mixture is wet-pulverized to produce the first sulfide solid electrolyte.
  • the wet-pulverization can be carried out in a manner similar to that described for the solid-phase method.
  • the crystal structure of the wet-pulverized first sulfide solid electrolyte obtained through the above process is not particularly limited.
  • sulfide solid electrolytes having a crystal structure containing Li, P, and S elements such as Li 7 P 3 S 11, which are called LPS-based
  • sulfide solid electrolytes having a crystal structure containing Li, Ge, P, and S elements such as Li 10 GeP 2 S 12 , which are called LGPS-based
  • sulfide solid electrolytes having an Argyrodite-type crystal structure containing Li, P, S, and Ha elements sulfide solid electrolytes made of Li-P-S-Ha-based crystallized glass, and sulfide solid electrolytes having other crystal structures
  • the above may be a sulfide solid electrolyte containing a crystalline phase and an amorphous phase.
  • the argyrodite-type crystal structure is a crystal structure possessed by a group of compounds derived from a mineral represented by the composition formula Ag 8 GeS 6.
  • the sulfide solid electrolyte is not limited to the above crystal structure, and some elements may be substituted with other elements.
  • the Ha element more preferably contains at least one element selected from the group consisting of Cl, Br, and I, and further preferably contains two or more elements. Moreover, the sulfide solid electrolyte more preferably contains at least one of Cl and Br as the Ha element, and even more preferably contains Cl and Br.
  • the argyrodite-type crystal structure preferably has the above structure, and the composition formula is preferably represented by Li ⁇ PS ⁇ Ha ⁇ , and the relationships 5 ⁇ 7, 4 ⁇ ⁇ 6, and 1.3 ⁇ 2 are satisfied.
  • the element ratios more preferably satisfy the relationships 5.1 ⁇ 6.3, 4 ⁇ 5.3, and 1.4 ⁇ 1.9, and further preferably satisfy the relationships 5.2 ⁇ 6.2, 4.1 ⁇ 5.2, and 1.5 ⁇ 1.8. That is, ⁇ is preferably 5 or more, more preferably more than 5.1, even more preferably more than 5.2, and is preferably 7 or less, more preferably less than 6.3, and even more preferably less than 6.2.
  • ⁇ is preferably 4 or more, more preferably more than 4, and even more preferably more than 4.1, and is preferably 6 or less, more preferably less than 5.3, and even more preferably less than 5.2.
  • ⁇ is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.5 or more, and is preferably 2 or less, more preferably 1.9 or less, and even more preferably 1.8 or less.
  • a portion of the S element may be substituted with Ha element, O element, Se, Te, BH 4 , CN, etc.
  • a portion of the P element may be substituted with Si element, Al element, Sn element, In element, Cu element, Sb element, Ge element, etc.
  • the first sulfide solid electrolyte in this manufacturing method contains carbon as an organic component derived from the solvent used in the wet grinding.
  • the amount of such carbon is, for example, preferably 3 mass% or less, more preferably 1.5 mass% or less, and even more preferably 1 mass% or less, relative to the first sulfide solid electrolyte.
  • the amount of carbon refers to the amount of carbon element in the first sulfide solid electrolyte, and can be measured, for example, by oxygen stream combustion-infrared absorption method using a sulfur carbon analyzer (CS844, manufactured by LECO Japan LLC).
  • the wet-ground first sulfide solid electrolyte is heated and melted to obtain a melt.
  • the method of heating and melting can be the same as that of the melting method described above.
  • the first sulfide solid electrolyte may be heated and melted together with the sulfide solid electrolyte raw material.
  • the mixture obtained by mixing the first sulfide solid electrolyte and the sulfide solid electrolyte raw material may be heated and melted, or the sulfide solid electrolyte raw material may be added to a melt obtained by heating and melting the first sulfide solid electrolyte, or the first sulfide solid electrolyte may be added to a melt obtained by heating and melting the sulfide solid electrolyte raw material.
  • the sulfide solid electrolyte raw material may be heated and melted together with the wet-pulverized first sulfide solid electrolyte.
  • the same sulfide solid electrolyte raw material as described in the above section [Wet-pulverized first sulfide solid electrolyte] can be used.
  • the temperature for heating and melting the first sulfide solid electrolyte is preferably 600°C or higher, and more preferably 700°C or higher, from the viewpoint of homogeneity of the melt.
  • the temperature for heating and melting is preferably 1000°C or lower, more preferably 950°C or lower, even more preferably less than 900°C, and particularly preferably less than 800°C, from the viewpoint of suppressing deterioration and decomposition of the components in the melt due to heating.
  • the above temperature is preferably 600°C or higher and less than 1000°C.
  • Carbon Removal In this manufacturing method, carbon is removed from a melt obtained by heating and melting the first sulfide solid electrolyte.
  • "removing" carbon from the melt means reducing the amount of carbon contained in the melt, and is not limited to completely eliminating carbon in the melt.
  • the amount of carbon in the melt before and after the removal may be reduced by 0.5% by mass or more, or may be reduced by 0.1% by mass or more.
  • the method for removing carbon from the melt is not particularly limited, but examples thereof include the following method 1 and method 2.
  • Method 1 includes a method of removing carbon from the melt by introducing a sulfur source into the melt. By introducing a sulfur source into the melt, carbon in the melt reacts with sulfur in the sulfur source, and carbon in the melt is discharged and removed as CS2 gas.
  • the sulfur source examples include organic sulfur compounds such as elemental sulfur, hydrogen sulfide, and carbon disulfide, iron sulfide (FeS, Fe 2 S 3 , FeS 2 , Fe 1-x S, etc.), bismuth sulfide (Bi 2 S 3 ), copper sulfide (CuS, Cu 2 S, Cu 1-x S, etc.), polysulfides such as lithium polysulfide and sodium polysulfide, polysulfides, and rubber vulcanized with sulfur. Elemental sulfur is particularly preferred as the sulfur source.
  • the sulfur source may be introduced into the melt as a gas, or as a powder of the sulfur source.
  • the method for introducing the sulfur source as a gas into the melt can be a conventionally known method, for example, a method in which sulfur powder is heated at 200° C. or more and 400° C. or less to vaporize the sulfur gas and introduce it into the melt.
  • the method of introducing the sulfur source powder into the melt can be, for example, adding the powder directly above the melt using a constant-volume feeder.
  • the average particle size of the powder is preferably 1 to 5000 ⁇ m from the viewpoint of homogenization.
  • the average particle size is preferably 1 ⁇ m or more, more preferably 10 ⁇ m or more, even more preferably 100 ⁇ m or more, and preferably 5000 ⁇ m or less, more preferably 2500 ⁇ m or less, and even more preferably 1000 ⁇ m or less.
  • the average particle size refers to the median diameter (D50) at which 50 volume percent of the particles have a particle size below this value, which is determined from a volume-based particle size distribution chart obtained by measuring the particle size distribution using a particle size distribution meter using a laser diffraction method.
  • the carbon amount A in the first sulfide solid electrolyte i.e., the sulfur amount B introduced relative to the carbon amount A in the melt, preferably satisfies A/B ⁇ 0.2 in weight ratio, and more preferably satisfies A/B ⁇ 0.1.
  • the carbon amount A means the amount of carbon element in the first sulfide solid electrolyte or the melt.
  • the sulfur amount B means the amount of sulfur element in the sulfur source introduced.
  • A/B is more preferably 0.05 or less, even more preferably 0.03 or less, and particularly preferably 0.01 or less.
  • the carbon amount A and the sulfur amount B can be measured by an oxygen stream combustion-infrared absorption method using, for example, a sulfur-carbon analyzer (CS844, manufactured by LECO Japan LLC).
  • Method 2 includes a method of removing carbon from the melt by introducing a sulfur source into the first sulfide solid electrolyte and heating and melting it.
  • a sulfur source into the first sulfide solid electrolyte
  • carbon in the melt reacts with sulfur in the sulfur source during subsequent heating and melting, and carbon in the melt is discharged and removed as CS2 gas.
  • the sulfur source and the method of introducing it can be the same as those in Method 1.
  • the weight ratio of the amount of sulfur B to be introduced relative to the amount of carbon A in the first sulfide solid electrolyte preferably satisfies A/B ⁇ 0.2, and more preferably satisfies A/B ⁇ 0.1.
  • the amount of carbon A means the amount of carbon in the first sulfide solid electrolyte or in the melt.
  • the amount of sulfur B means the amount of sulfur in the sulfur source to be introduced.
  • A/B is more preferably 0.05 or less, even more preferably 0.03 or less, and particularly preferably 0.01 or less.
  • the carbon amount A and the sulfur amount B can be measured by an oxygen stream combustion-infrared absorption method using, for example, a sulfur-carbon analyzer (CS844, manufactured by LECO Japan LLC).
  • a sulfur source is introduced into the first sulfide solid electrolyte, which not only makes it possible to remove carbon from the molten liquid during subsequent heating and melting, but also makes it possible to suppress changes in the sulfur composition that accompany volatilization.
  • the present production method includes a step of cooling the melt from which carbon has been removed by the above method. This results in a second sulfide solid electrolyte, which will be described later.
  • the melt can be cooled by the same method as described in the above section [Wet-ground first sulfide solid electrolyte].
  • the lithium ion conductivity of the second sulfide solid electrolyte is preferably 1.0 ⁇ 10 -4 S/cm or more, more preferably 5.0 ⁇ 10 -4 S/cm or more, still more preferably 1.0 ⁇ 10 -3 S/cm or more, and particularly preferably 5.0 ⁇ 10 -3 S/cm or more.
  • the lithium ion conductivity is measured using an AC impedance measuring device (for example, Potentiostat/Galvanostat VSP manufactured by Bio-Logic Sciences Instruments) under the following measurement conditions: measurement frequency: 100 Hz to 1 MHz, measurement voltage: 100 mV, and measurement temperature: 25°C.
  • the obtained second sulfide solid electrolyte can be identified by analyzing the crystal structure using X-ray diffraction (XRD) measurement, and analyzing the elemental composition using various methods such as ICP optical emission spectrometry, atomic absorption spectrometry, and ion chromatography.
  • ICP optical emission spectrometry atomic absorption spectrometry
  • ion chromatography ion chromatography
  • the present manufacturing method may further include annealing the second sulfide solid electrolyte.
  • the ions in the crystal structure can be rearranged to increase the lithium ion conductivity.
  • the annealing treatment refers to at least one of annealing the second sulfide solid electrolyte obtained by cooling for crystallization and rearranging the ions in the crystal structure.
  • the heating treatment of these amorphous sulfide solid electrolytes or sulfide solid electrolytes containing an amorphous phase is referred to as the annealing treatment, including the crystallization treatment.
  • the annealing process is preferably performed by heating at 340°C or higher, more preferably at 380°C or higher, and may also be performed by heating at 550°C or lower, or at 500°C or lower.
  • the composition of the second sulfide solid electrolyte may be further adjusted by appropriately adding other sulfide solid electrolytes or sulfide solid electrolyte raw materials to the second sulfide solid electrolyte.
  • a method for adjusting the composition for example, the method described in JP 2015-5352 A or the like can be adopted.
  • the present manufacturing method it is preferable to perform the heating and melting of the first sulfide solid electrolyte and the cooling of the melt from which carbon has been removed as a continuous process.
  • the melt from which carbon has been removed obtained in the furnace is continuously discharged and transferred to a cooling process to continuously manufacture the second sulfide solid electrolyte.
  • This allows a series of steps, including the introduction of the first sulfide solid electrolyte, heating and melting, discharging the melt, and cooling, to be performed continuously, and the second sulfide solid electrolyte can be produced in large quantities more efficiently in a short time.
  • a method for recycling a sulfide solid electrolyte according to an embodiment of the present invention (hereinafter also referred to as the present recycling method) is characterized in that it includes heating and melting a wet-pulverized sulfide solid electrolyte to obtain a molten liquid, removing carbon from the molten liquid, and cooling the molten liquid from which the carbon has been removed to obtain a regenerated sulfide solid electrolyte.
  • This recycling method includes the same steps as the manufacturing method described above, and the "wet-pulverized sulfide solid electrolyte" in this recycling method corresponds to the "wet-pulverized first sulfide solid electrolyte” in this manufacturing method, and the “recycled sulfide solid electrolyte” corresponds to the "second sulfide solid electrolyte.”
  • the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.
  • the present invention is not limited to the above-described embodiments, and modifications and improvements can be made as appropriate.
  • the material, shape, dimensions, number, and location of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.
  • the present specification discloses the following: [1] Heating and melting a wet-pulverized first sulfide solid electrolyte to obtain a melt, and removing carbon from the melt; and cooling the melt from which the carbon has been removed to obtain a second sulfide solid electrolyte;
  • the method for producing a sulfide solid electrolyte includes the steps of: [2] The method for producing a sulfide solid electrolyte according to the above [1], further comprising removing carbon from the melt by introducing a sulfur source into the melt.
  • Example 1 is a comparative example
  • Examples 2 and 3 are examples of the present manufacturing method
  • Example 4 is a reference example.
  • the powder obtained in each example was further crushed in a mortar and passed through a 100 ⁇ m mesh to obtain a sulfide solid electrolyte powder having a D50 of 10 ⁇ m according to the volumetric particle size distribution.
  • the powder was compressed at a pressure of 380 MPa to obtain a measurement sample, and the lithium ion conductivity was measured using an AC impedance measurement device (potentiostat/galvanostat VSP, manufactured by Bio-Logic Sciences Instruments) and evaluated according to the following criteria.
  • the measurement conditions were as follows: measurement frequency: 100 Hz to 1 MHz, measurement voltage: 100 mV, and measurement temperature: 25°C.
  • the results of each example are shown in Table 1.
  • sulfide solid electrolyte pellets (argyrodite-type crystal structure, composition: Li5.4PS4.4Cl0.8Br0.8 , manufactured by AGC, no composition deviation ) were crushed using a cutter mill to obtain coarse-grained dry powder , which was then hand-pulverized (coarsely crushed) in a mortar, and sulfide solid electrolyte particles having a size of 100 ⁇ m or less were selected using a sieve with openings of 100 ⁇ m or less.
  • a liquid medium for fine grinding was prepared.
  • the liquid medium was a mixed solvent (8 g) of 5 g of heptane (Kanto Chemical Co., Ltd., special grade (dehydrated - Super-) and 3 g of dibutyl ether (Tokyo Chemical Industry Co., Ltd., stabilized with BHT).
  • the mixed solvent was added with molecular sieves 4A 1/16 (Fujifilm Wako Pure Chemical Industries, Ltd.), left overnight or longer, and pre-dehydrated.
  • the slurry and the alumina balls were separated using a stainless steel sieve (opening 100 ⁇ m), and the mixed solvent was poured several times over the balls remaining on the sieve to wash away the slurry adhering to the ball surfaces and collect them.
  • the mixture was left to stand for 3 to 5 hours, and the supernatant liquid was removed.
  • the resulting slurry was placed in a bottle and then placed in a separable flask (500 mL) inserted in a mantle heater in a glove box. Then, the mixture was heated at 150°C for 2 hours while circulating N2 gas at 1.5 L/min, and then further heated at 190°C for 4 hours to dry the mixture.
  • Example 4 The sulfide solid electrolyte pellets (argyrodite type crystal structure, composition: Li 5.4 PS 4.4 Cl 0.8 Br 0.8 , manufactured by AGC) used in Examples 1 to 3 were used as the sulfide solid electrolyte of Example 4.
  • Examples 2 and 3 the amount of carbon derived from the solvent during wet grinding was reduced because a process of removing carbon from the melt obtained by heating and melting the wet-ground first sulfide solid electrolyte was performed, and as a result, the lithium ion conductivity of the obtained second sulfide solid electrolyte was high.
  • the carbon was removed, and therefore the external color was white or yellow, rather than black, which is derived from carbon (soot).
  • Example 1 which is a comparative example, a process of removing carbon from the melt was not performed, so the amount of carbon derived from the solvent during wet grinding was large, and the lithium ion conductivity of the finally obtained sulfide solid electrolyte was low.
  • the carbon was not removed, so the external color was black derived from carbon (soot).
  • Example 4 is a reference example, and since wet pulverization was not performed in Example 4, the carbon amount in the sulfide solid electrolyte was small.
  • a sulfide solid electrolyte with excellent lithium ion conductivity can be produced by a melting method using a sulfide solid electrolyte.

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JP2010248045A (ja) * 2009-04-17 2010-11-04 Sumitomo Electric Ind Ltd ＬｉＮｂＯ３ガラス並びにその製造方法およびＬｉＮｂＯ３ガラスを用いた非水電解質電池
JP2013075816A (ja) * 2011-09-13 2013-04-25 Nippon Chem Ind Co Ltd 硫化リチウム、その製造方法及び無機固体電解質の製造方法
JP2015005372A (ja) 2013-06-19 2015-01-08 出光興産株式会社 硫化物系固体電解質の製造方法
JP2015005352A (ja) 2013-06-19 2015-01-08 住友電装株式会社 ワイヤーハーネス
JP2015060737A (ja) * 2013-09-19 2015-03-30 株式会社村田製作所 全固体電池およびその製造方法
WO2016068040A1 (ja) * 2014-10-27 2016-05-06 国立研究開発法人産業技術総合研究所 リチウム含有ガーネット結晶体および全固体リチウムイオン二次電池
JP2023112311A (ja) 2022-02-01 2023-08-14 Ｍａｒｉ－Ｃｉｅｌ株式会社 人的トラブル発生のリスク予測方法、予測プログラムおよび予測システム

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010248045A (ja) * 2009-04-17 2010-11-04 Sumitomo Electric Ind Ltd ＬｉＮｂＯ３ガラス並びにその製造方法およびＬｉＮｂＯ３ガラスを用いた非水電解質電池
JP2013075816A (ja) * 2011-09-13 2013-04-25 Nippon Chem Ind Co Ltd 硫化リチウム、その製造方法及び無機固体電解質の製造方法
JP2015005372A (ja) 2013-06-19 2015-01-08 出光興産株式会社 硫化物系固体電解質の製造方法
JP2015005352A (ja) 2013-06-19 2015-01-08 住友電装株式会社 ワイヤーハーネス
JP2015060737A (ja) * 2013-09-19 2015-03-30 株式会社村田製作所 全固体電池およびその製造方法
WO2016068040A1 (ja) * 2014-10-27 2016-05-06 国立研究開発法人産業技術総合研究所 リチウム含有ガーネット結晶体および全固体リチウムイオン二次電池
JP2023112311A (ja) 2022-02-01 2023-08-14 Ｍａｒｉ－Ｃｉｅｌ株式会社 人的トラブル発生のリスク予測方法、予測プログラムおよび予測システム

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