Method for producing sulfide solid electrolyte

Abstract

This method for producing a sulfide solid electrolyte involves mixing, in a solvent, raw material-containing matter that includes multiple kinds of raw materials each including at least one atom selected from a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom, and subsequentially heating same, wherein the raw material-containing matter includes elemental sulfur and lithium sulfide, and the use amount of elemental sulfur is more than 1.0 mol based on 1.0 mol of the lithium sulfide.

Description

Method for producing sulfide solid electrolyte

[0001] The present invention relates to a method for producing a sulfide solid electrolyte.

[0002] With the recent rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries to be used as their power sources has become increasingly important. Conventionally, batteries used for such applications have used electrolytes containing flammable organic solvents, but by making batteries 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, batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed.

[0003] Methods for producing solid electrolytes used in solid electrolyte layers are broadly divided into solid-phase methods and liquid-phase methods. 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. For example, among the liquid-phase methods, a homogeneous method in which the solid electrolyte is dissolved in a solvent and re-precipitated is known (see, for example, Patent Document 1). Also, heterogeneous methods include a method in which a solid electrolyte raw material such as lithium sulfide is reacted in a solvent containing a polar aprotic solvent (see, for example, Patent Documents 2 and 3). Furthermore, a method for producing a solid electrolyte using a specific compound having an amino group as a complexing agent (see, for example, Patent Documents 4 and 5) is also known. Non-Patent Document 1 describes a method for producing a solid electrolyte by using tetrahydrofuran and ethanol to prepare a complexing agent containing Li. ６ P.S. ５ A tetrahydrofuran-ethanol precursor solution of Br was prepared, dried, and heated to obtain Li. ６ P.S. ５ It is described that a solid electrolyte having an argyrodite-type crystal structure with a composition of Br is prepared.

[0004] In addition, Non-Patent Documents 2 and 3 disclose a method for the preparation of a tetrahydrofuran-ethanol mixture of acetonitrile, tetrahydrofuran, and ethanol (volume ratio: 1:1:0.05) containing Li ２ S, P ２ S ５By adding S (molar ratio of 7:3:x (x = 3, 5, or 7)), lithium polysulfides and highly reactive sulfur radicals are generated, and after stirring for several minutes, the mixture is dried under vacuum and heated at a heating temperature of 270 ° C., 350 ° C., etc. to produce Li ７ P ３ S １１ It is described that a crystalline solid electrolyte having the following composition is produced.

[0005] Japanese Patent Application Publication No. 2014-191899 International Publication No. 2014 / 192309 Pamphlet International Publication No. 2018 / 054709 Pamphlet International Publication No. 2020 / 105737 Pamphlet International Publication No. 2021 / 230189 Pamphlet

[0006] J. Mater. Chem. A, 2019, 7, 558-566 Proceedings of the 62nd Battery Symposium, published on November 29, 2021, All-solid-state battery / Sulfide-based electrolyte, 3E01Adv. Energy Sustainability Res. 2022, 3, 2200019

[0007] The present invention has been made in view of the above circumstances, and has an object to efficiently provide a sulfide solid electrolyte with improved ionic conductivity.

[0008] A method for producing a sulfide solid electrolyte according to the present invention includes: mixing, in a solvent, a raw material content containing a plurality of raw materials each containing at least one atom selected from a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom; and subsequently heating the raw material content, wherein the raw material content contains elemental sulfur and lithium sulfide, and the amount of the elemental sulfur used is more than 1.0 mol per 1.0 mol of the lithium sulfide.

[0009] According to the present invention, it is possible to efficiently provide a sulfide solid electrolyte with improved ionic conductivity.

[0010] 1 is an X-ray diffraction spectrum of a powder obtained in an example. 2 is an X-ray diffraction spectrum of a powder obtained in an example. 3 is an X-ray diffraction spectrum of a powder obtained in an example. 4 is an X-ray diffraction spectrum of a powder obtained in an example and a comparative example. 5 is an X-ray diffraction spectrum of a powder obtained in an example and a comparative example. 6 is an X-ray diffraction spectrum of a powder obtained in an example and a comparative example. 7 is an X-ray diffraction spectrum of a powder obtained in an example. 8 is an X-ray diffraction spectrum of a powder obtained in an example. 9 is an X-ray diffraction spectrum of a powder obtained in an example. 10 is an X-ray diffraction spectrum of a powder obtained in an example. 11 is an X-ray diffraction spectrum of a powder obtained in an example. 12 is an X-ray diffraction spectrum of a powder obtained in an example. 13 is an X-ray diffraction spectrum of a powder obtained in an example. 14 is an X-ray diffraction spectrum of a powder obtained in an example. 15 is an X-ray diffraction spectrum of a powder obtained in an example. 16 is an X-ray diffraction spectrum of a powder obtained in an example. 17 is an X-ray diffraction spectrum of a powder obtained in an example. 18 is an X-ray diffraction spectrum of a powder obtained in an example. 19 is an X-ray diffraction spectrum of a powder obtained in an example. 19 is an X-ray diffraction spectrum of a powder obtained in an example. 1 shows an X-ray diffraction spectrum of the powder obtained in the example. 2 shows an X-ray diffraction spectrum of the powder obtained in the example. 3 shows an X-ray diffraction spectrum of the powder obtained in the example.

[0011] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a numerical range expressed as "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​of the examples can also be used as the upper and lower limit values. Furthermore, preferred specifications can be arbitrarily adopted. In other words, one preferred specification can be adopted in combination with one or more other preferred specifications. It can be said that a combination of preferred items is more preferable.

[0012] (Findings Obtained by the Inventors to Achieve the Present Invention) The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found the following, which has led to the completion of the present invention.

[0013] In recent years, in order to put all-solid-state batteries into practical use, liquid phase methods have been attracting attention as a method that can be easily synthesized in large quantities, in addition to versatility and applicability. Solid phase methods include a method of obtaining a solid electrolyte by grinding and mixing solid electrolyte raw materials in a grinder and causing a reaction, as typified by a mechanical milling method. However, this method requires high equipment costs and a large initial investment, making it difficult to reduce costs. On the other hand, as for the liquid phase method, for example, the method described in Patent Document 1 uses Li ２ S and P ２ S ５ The method described in Patent Document 2 involves mechanically milling a mixture of Li and ZnO (80:20) for 20 hours, dissolving it in N-methylformamide (NMF), and drying it to obtain a solid electrolyte, which requires 20 hours of mechanical milling. ２ S and P ２ S ５ The method described in Patent Document 3 involves contacting and reacting Li with dimethoxyethane (DME). ３ P.S. ４ - When producing DME (electrolyte precursor; complex), stirring is performed for about 10 days. Furthermore, in the methods using a complexing agent described in Patent Documents 4 and 5, the solid electrolyte raw material is stirred with the complexing agent for 12 to 72 hours, or even longer, to allow the reaction to proceed. Also, in the method described in Non-Patent Document 1, the reaction is carried out overnight, i.e., for about 12 hours. As such, since the production methods according to conventional technologies require long reaction times, there is a demand for better production efficiency.

[0014] In addition, in the method described in Non-Patent Document 1, drying is performed for 3 hours to remove tetrahydrofuran and ethanol. However, a reaction between some of the remaining ethanol and the solid electrolyte may produce oxides as impurities. ２ A part of S reacts with an alcohol solvent such as ethanol to produce lithium alkoxide such as lithium ethoxide, and Li ２Phosphorus sulfide (e.g., diphosphorus pentasulfide (P ２ S ５ As a result, the purity of the sulfide solid electrolyte may decrease, and the ionic conductivity may also decrease, so there is a need to improve the quality.

[0015] In the methods described in Non-Patent Documents 2 and 3, a crystalline sulfide solid electrolyte is obtained by stirring for several minutes, drying for one hour, and heating for one hour, and it can be said that this method has excellent production efficiency. However, since it does not contain halogen atoms, the ionic conductivity is about 0.9 to 1.3 mS / cm, and it cannot be said that this sulfide solid electrolyte has high ionic conductivity. Furthermore, these Non-Patent Documents state that the action of ethanol on the lithium of lithium polysulfide generates highly reactive sulfur radicals. Therefore, Li ２ When a lithium halide or the like containing Li as well as S is used as a raw material, it is expected that the mechanism of generating sulfur radicals will be inhibited, and the reaction will not proceed efficiently. As such, the conventional techniques have both advantages and disadvantages, and there is room for improvement in producing a sulfide solid electrolyte having high ionic conductivity with high production efficiency.

[0016] Therefore, the present inventors focused on elemental sulfur as a raw material and investigated the use of elemental sulfur as a raw material and a raw material containing a halogen atom to improve ionic conductivity. They found that by using an excess amount of elemental sulfur, a sulfide solid electrolyte with improved ionic conductivity could be obtained in an extremely short time.

[0017] (Regarding various aspects of the present embodiment) A method for producing a sulfide solid electrolyte according to a first aspect of the present embodiment includes: mixing, in a solvent, a raw material content containing a plurality of raw materials each containing at least one atom selected from a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom; and then heating the raw material content, wherein the raw material content contains elemental sulfur and lithium sulfide, and the amount of the elemental sulfur used is more than 1.0 mol per 1.0 mol of the lithium sulfide.

[0018] The method for producing a sulfide solid electrolyte according to this embodiment requires the use of a combination of elemental sulfur and lithium sulfide as raw materials. It is believed that elemental sulfur reacts with lithium sulfide in a solvent to form lithium polysulfides, generating sulfur radicals. The sulfur radicals are highly reactive, and promote reactions with other raw materials, such as diphosphorus pentasulfide and other raw materials containing halogen atoms, to generate soluble polysulfides (hereinafter simply referred to as "polysulfides"), which are precursors of the sulfide solid electrolyte (hereinafter also referred to as "electrolyte precursors"). It is believed that decomposing these polysulfides by heating or the like can efficiently produce a sulfide solid electrolyte with improved ionic conductivity.

[0019] Furthermore, the amount of elemental sulfur used is more than 1.0 mol per 1.0 mol of lithium sulfide, which is an excessive amount. This amount, which will be described in detail later, is also an excessive amount compared to the sulfur atoms required for the sulfide solid electrolyte to be obtained. In this way, the use of excess elemental sulfur promotes the generation of sulfur radicals, and as a result, a sulfide solid electrolyte with improved ionic conductivity can be efficiently produced.

[0020] By mixing the above raw material components, a precursor for generating a sulfide solid electrolyte by further heating, an amorphous sulfide solid electrolyte, or even a crystalline sulfide solid electrolyte can be produced. Mixing generates a soluble polysulfide, which is an electrolyte precursor. Then, by heating, the polysulfide is decomposed to form an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, and the crystallinity of the crystalline sulfide solid electrolyte is improved. The solvent is also removed. Therefore, in the manufacturing method of this embodiment, heating is performed primarily for the decomposition of the polysulfide, removal of the solvent, and crystallization. The elemental sulfur generated by the decomposition of the polysulfide can also be removed by evaporation through heating, but methods other than heating, such as solvent washing or hydrodesulfurization, may also be used.

[0021] A second aspect of the present embodiment is directed to the method for producing a sulfide solid electrolyte of the first aspect, wherein the halogen atom is at least one atom selected from a chlorine atom, a bromine atom, and an iodine atom.

[0022] When a sulfide solid electrolyte contains a halogen atom, it has high ionic conductivity. In particular, when a sulfide solid electrolyte contains a chlorine atom, a bromine atom, or an iodine atom, it is easy to form an argyrodite-type crystal structure or a thiolicon region II-type crystal structure, which exhibits particularly high ionic conductivity.

[0023] A method for producing a sulfide solid electrolyte according to a third aspect of the present embodiment is the same as the method for producing a sulfide solid electrolyte according to the first or second aspect above, except that the solvent is an organic solvent containing at least one atom selected from oxygen atoms and nitrogen atoms. A method for producing a sulfide solid electrolyte according to a fourth aspect of the present embodiment is the same as the method for producing a sulfide solid electrolyte according to the first to third aspects above, except that the solvent is at least one organic solvent selected from alcohol solvents, ether solvents, and nitrile solvents.

[0024] When a heteroatom-containing solvent is used as the solvent, the generation of sulfur radicals is promoted via the reaction of elemental sulfur with lithium sulfide to form lithium polysulfides. Because sulfur radicals are highly reactive, they react with other raw materials, such as diphosphorus pentasulfide and other raw materials containing halogen atoms, and react with lithium sulfide or lithium polysulfides to promote the generation of soluble polysulfides. This soluble polysulfide is a precursor to a sulfide solid electrolyte, and heating the polysulfide decomposes it to rapidly form an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte, improving the crystallinity of the crystalline sulfide solid electrolyte. As a result, a sulfide solid electrolyte with few impurities and high ionic conductivity can be efficiently obtained.

[0025] Furthermore, as the solvent containing such a heteroatom, it is preferable to use at least one of an alcohol solvent, an ether solvent, and a nitrile solvent. By using these solvents, the effects of using the solvent containing the heteroatom, namely, the generation of sulfur radicals and the formation of an electrolyte precursor (polysulfide) are promoted. Furthermore, by using an alcohol solvent, an ether solvent, and a nitrile solvent in combination, the generation of sulfur radicals and the formation of an electrolyte precursor (polysulfide) are promoted in a balanced manner. As a result, a sulfide solid electrolyte with few impurities and high ionic conductivity can be efficiently obtained.

[0026] A fifth aspect of the present embodiment is a method for producing a sulfide solid electrolyte according to any one of the first to fourth aspects, wherein the solvent comprises an alcohol solvent. A sixth aspect of the present embodiment is a method for producing a sulfide solid electrolyte according to any one of the first to fifth aspects, wherein the solvent comprises an alcohol solvent and at least one organic solvent selected from an ether solvent and a nitrile solvent.

[0027] Among the heteroatom-containing solvents, the alcohol solvents, ether solvents, and nitrile solvents are effective in generating sulfur radicals and forming electrolyte precursors (polysulfides), and among these, alcohol solvents are particularly effective in promoting the generation of sulfur radicals and the formation of electrolyte precursors (polysulfides). By using an alcohol solvent, a sulfide solid electrolyte with few impurities and high ionic conductivity can be more efficiently produced.

[0028] It is also effective to use an alcohol solvent and at least one of an ether solvent and a nitrile solvent as the alcohol solvent, ether solvent, and nitrile solvent, which facilitates the balanced promotion of the generation of sulfur radicals and the formation of the electrolyte precursor (polysulfide).

[0029] A seventh aspect of the present embodiment is a method for producing a sulfide solid electrolyte according to any one of the first to sixth aspects, wherein the solvent is an organic solvent including an alcohol solvent, an ether solvent, and a nitrile solvent.

[0030] The method for producing a sulfide solid electrolyte according to an eighth aspect of the present embodiment is the method for producing a sulfide solid electrolyte according to any one of the fifth to seventh aspects, wherein the amount of the alcohol solvent used is 0.005 mol or more and 20.0 mol or less per 1.0 mol of the lithium sulfide. The method for producing a sulfide solid electrolyte according to a ninth aspect is the method for producing a sulfide solid electrolyte according to the sixth to eighth aspects, wherein the total amount of the ether solvent and the nitrile solvent used is 2.0 parts by volume or more and 10,000.0 parts by volume or less per 1.0 part by volume of the alcohol solvent used.

[0031] As described above, the use of a solvent containing a heteroatom promotes the generation of sulfur radicals and the formation of an electrolyte precursor (polysulfide), and the use of an alcohol solvent in particular improves the effect of forming the electrolyte precursor (polysulfide). In this case, by setting the amount of the alcohol solvent used within the above range, the generation of sulfur radicals and the formation of the electrolyte precursor (polysulfide) are further promoted. Furthermore, by setting the total amount of the ether solvent and the nitrile solvent used within the above range, the generation of sulfur radicals and the formation of the electrolyte precursor (polysulfide) are further promoted.

[0032] A tenth aspect of the present embodiment is a method for producing a sulfide solid electrolyte according to any one of the first to ninth aspects, wherein the heating temperature in the heating step is 20°C or higher and lower than 500°C. A eleventh aspect of the present embodiment is a method for producing a sulfide solid electrolyte according to any one of the first to tenth aspects, wherein the heating step is performed by a first heating step having a heating temperature of 20°C or higher and lower than 150°C, and a second heating step having a heating temperature of 150°C or higher and 500°C or lower.

[0033] As described above, in the production method of this embodiment, heating is performed mainly for the decomposition of the electrolyte precursor (polysulfide), removal of the solvent, and crystallization. When the heating temperature is within the above range, it is possible to more efficiently and reliably remove the solvent and perform crystallization. Furthermore, by performing heating in multiple stages, including the first heating and the second heating, it is possible to more efficiently perform the decomposition of the polysulfide, removal of the solvent, and crystallization. Furthermore, heating can also remove elemental sulfur produced by the decomposition of the polysulfide. The removal of elemental sulfur is not limited to heating, and can also be performed by other methods such as solvent washing and hydrodesulfurization.

[0034] A method for producing a sulfide solid electrolyte according to a twelfth aspect of the present embodiment is the same as any one of the first to eleventh aspects, except that in the mixing, the raw materials are mixed simultaneously. A method for producing a sulfide solid electrolyte according to a thirteenth aspect is the same as any one of the first to eleventh aspects, except that in the mixing, a raw material group 1 including some raw materials selected from the raw materials is mixed, and then a raw material group 2 including raw materials other than the some raw materials is mixed.

[0035] In the manufacturing method of this embodiment, the order in which the raw materials are supplied is not particularly limited, but from the viewpoint of easier operation, it is preferable to mix all the raw materials simultaneously (which may also be referred to as "lump mixing"). Also, in consideration of obtaining higher solubility and ionic conductivity of the raw materials, it is preferable to divide the raw materials into two groups described below and mix them sequentially (which may also be referred to as "divided mixing"). In the manufacturing method of this embodiment, whether to use bulk mixing or divided mixing can be selected appropriately depending on whether ease of operation or ionic conductivity is more important.

[0036] A fourteenth aspect of the present embodiment relates to the method for producing a sulfide solid electrolyte of the thirteenth aspect, wherein the raw material group 1 includes elemental sulfur. A fifteenth aspect relates to the method for producing a sulfide solid electrolyte of the thirteenth or fourteenth aspect, wherein the raw material group 1 includes a raw material including at least one atom selected from a lithium atom, a phosphorus atom, and a sulfur atom, elemental sulfur, and lithium sulfide, and the raw material group 2 includes a raw material including a halogen atom.

[0037] When the raw materials are mixed in two stages, it is preferable that raw material group 1 contains elemental sulfur, that is, elemental sulfur is mixed first. Because sulfur radicals can be formed first, a sulfide solid electrolyte with improved ionic conductivity can be efficiently produced.

[0038] Furthermore, from the viewpoint of reducing the amount of remaining raw materials and obtaining higher ionic conductivity, it is preferable to allocate a raw material containing at least one atom selected from a lithium atom, a phosphorus atom, and a sulfur atom, and a raw material containing a halogen atom to either raw material group 1 or 2.

[0039] From the viewpoint of efficiently producing a sulfide solid electrolyte having improved ionic conductivity by further promoting the formation of sulfur radicals via lithium polysulfides and the formation of an electrolyte precursor, it is particularly preferable that raw material group 1 includes a raw material containing at least one atom selected from lithium atoms, phosphorus atoms, and sulfur atoms, elemental sulfur, and lithium sulfide, and that raw material group 2 includes a raw material containing a halogen atom.

[0040] A method for producing a sulfide solid electrolyte according to a sixteenth aspect of the present embodiment is any one of the first to fifteenth aspects, wherein a crystalline sulfide solid electrolyte having an argyrodite-type crystal structure or a thiolisiconregion II-type crystal structure is produced.

[0041] In the manufacturing method of this embodiment, it is possible to manufacture a desired sulfide solid electrolyte by changing the types and compounding ratios of the solid electrolyte raw materials contained in the raw material contents. Crystalline sulfide solid electrolytes having an argyrodite-type crystal structure and crystalline sulfide solid electrolytes having a thiolisiconregion II-type crystal structure are known as sulfide solid electrolytes with extremely high ionic conductivity, and are preferred as sulfide solid electrolytes to be obtained by the manufacturing method of this embodiment.

[0042] (Sulfide Solid Electrolyte) In this specification, the term "solid electrolyte" refers to an electrolyte that maintains a solid state under a nitrogen atmosphere at 25° C. The sulfide solid electrolyte in this embodiment is a solid electrolyte that contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms and has ionic conductivity due to the lithium atoms.

[0043] The term "sulfide solid electrolyte" includes both amorphous sulfide solid electrolytes and crystalline sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte refers to a sulfide solid electrolyte in which a peak derived from the solid electrolyte is observed in an X-ray diffraction pattern in an X-ray diffraction measurement, regardless of whether or not a peak derived from the raw materials of the sulfide solid electrolyte is present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and a portion of the crystalline structure may be derived from the solid electrolyte, or the entire crystalline structure may be derived from the solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may also contain an amorphous sulfide solid electrolyte in part. Therefore, crystalline sulfide solid electrolytes include so-called glass ceramics obtained by heating an amorphous sulfide solid electrolyte to a temperature equal to or higher than the crystallization temperature. In this specification, the amorphous sulfide solid electrolyte refers to an X-ray diffraction pattern in X-ray diffraction measurement that shows a halo pattern in which peaks other than those derived from the material are not substantially observed, regardless of whether or not peaks derived from the raw materials of the sulfide solid electrolyte are present.

[0044] [Method for Producing Sulfide Solid Electrolyte] A method for producing a sulfide solid electrolyte according to the present embodiment includes: mixing, in a solvent, a raw material content containing a plurality of raw materials each containing at least one atom selected from a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom; and then heating the raw material content, wherein the raw material content contains elemental sulfur and lithium sulfide, and the amount of the elemental sulfur used is more than 1.0 mol per 1.0 mol of the lithium sulfide.

[0045] [Mixing raw material ingredients] The production method of this embodiment includes mixing, in a solvent, raw material ingredients containing a plurality of raw materials each containing at least one atom selected from a lithium atom, a phosphorus atom, a sulfur atom, and a halogen atom. The production method of this embodiment will first be described, starting with the raw material ingredients.

[0046] (Raw Material Inclusions) The raw material inclusions used in this embodiment are inclusions containing a plurality of raw materials containing at least one atom selected from a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom, and contain elemental sulfur and lithium sulfide. That is, the raw material inclusions are inclusions containing at least elemental sulfur and lithium sulfide, and further containing a plurality of raw materials containing at least one atom selected from a lithium atom, a sulfur atom, a phosphorus atom, and a halogen atom.

[0047] Examples of raw materials contained in the raw material content include lithium sulfide; lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ ) and other phosphorus sulfides; various phosphorus fluorides (PF ３ , P.F. ５ ), various phosphorus chlorides (PCl ３ , PCl ５ , P ２ Cl ４ ), various phosphorus bromides (PBr ３ , PBr ５ ), various phosphorus iodides (PI ３ , P ２ I ４) and the like; phosphorus halides such as thiophosphoryl fluoride (PSF ３ ), thiophosphoryl chloride (PSCl ３ ), thiophosphoryl bromide (PSBr ３ ), thiophosphoryl iodide (PSI ３ ), thiophosphoryl fluoride dichloride (PSCl ２ F), thiophosphoryl fluoride dibromide (PSBr ２ a source material consisting of at least two atoms selected from the above four types of atoms, such as thiophosphoryl halides, e.g., fluorine (F); ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ), preferably chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ ) are typical examples.

[0048] Examples of materials that can be used as raw materials other than those mentioned above include raw materials that contain at least one atom selected from the above four types of atoms and also contain atoms other than the four types of atoms, more specifically, lithium compounds such as lithium oxide, lithium hydroxide, and lithium carbonate; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS ２ metal sulfides such as aluminum sulfide and zinc sulfide; 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 halides, antimony halides, tellurium halides and bismuth halides; phosphorus oxychloride (POCl ３ ), phosphorus oxybromide (POBr ３ ) and the like; and the like.

[0049] Among the above, lithium sulfide, diphosphorus trisulfide (P ２ S ３), diphosphorus pentasulfide (P ２ S ５ ) and other phosphorus sulfides, fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ and lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide are preferred. When oxygen atoms are introduced into the solid electrolyte, lithium oxide, lithium hydroxide, and phosphate compounds such as lithium phosphate are preferred.

[0050] The halogen atom is preferably a chlorine atom, a bromine atom, or an iodine atom, and preferably at least one selected from these. Therefore, the lithium halide is preferably lithium chloride, lithium bromide, or lithium iodide, and the halogen element is preferably chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２ These may be used alone or in combination of two or more.

[0051] Preferred examples of combinations of raw materials include a combination of lithium sulfide, elemental sulfur, diphosphorus pentasulfide, and a lithium halide, and a combination of lithium sulfide, elemental sulfur, diphosphorus pentasulfide, and an elemental halogen. Preferred lithium halides include lithium chloride, lithium bromide, and lithium iodide, and preferred halogens are chlorine, bromine, and iodine.

[0052] In this embodiment, PS ４ Li containing structure ３ P.S. ４ can also be used as part of the raw material. ３ P.S. ４ This is prepared by manufacturing or the like and used as a raw material. ３ P.S. ４ The content is preferably 60 to 100 mol %, more preferably 65 to 90 mol %, and even more preferably 70 to 80 mol %.

[0053] Also, Li ３ P.S. ４When using a halogen atom, Li ３ P.S. ４ The content of the halogen element is preferably 1 to 50 mol %, more preferably 10 to 40 mol %, even more preferably 20 to 30 mol %, and even more preferably 22 to 28 mol %.

[0054] The lithium sulfide used in this embodiment is preferably in the form of particles. ５０ ) is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.5 μm or more and 100 μm or less, and even more preferably 1 μm or more and 20 μm or less. ５０ ) is the particle size at which, when a particle size distribution cumulative curve is drawn, the cumulative total, starting from the smallest particle size, reaches 50% (volume basis) of the total, and the volume distribution refers to the average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device. Furthermore, among the above-mentioned examples of raw materials, solid raw materials preferably have an average particle size similar to that of the lithium sulfide particles. That is, raw materials within the same range as the average particle size of the lithium sulfide particles are preferred.

[0055] (Regarding the blending ratio of raw materials) In the production method of this embodiment, the amount of elemental sulfur used is more than 1.0 mol per 1.0 mol of lithium sulfide. By using an excess amount of elemental sulfur in this manner, the generation of sulfur radicals is promoted, and as a result, a sulfide solid electrolyte with improved ionic conductivity can be efficiently produced. From the viewpoint of more efficiently producing a sulfide solid electrolyte with improved ionic conductivity, the amount of elemental sulfur used is preferably 1.2 mols or more, more preferably 1.5 mols or more, and even more preferably 1.7 mols or more. There is no particular upper limit, but from the viewpoint of more efficiently obtaining a sulfide solid electrolyte, it may be about 4.0 mols or less, and preferably 3.0 mols or less.

[0056] The amount of elemental sulfur used is preferably 140% or more, more preferably 150% or more, even more preferably 160% or more, and still more preferably 170% or more of the sulfur atoms required to form the composition of the sulfide solid electrolyte to be obtained by the production method of this embodiment. There is no particular upper limit, but from the viewpoint of more efficiently obtaining a sulfide solid electrolyte, it may be about 300% or less, preferably 280% or less, more preferably 250% or less, and even more preferably 230% or less.

[0057] When lithium sulfide, elemental sulfur, diphosphorus pentasulfide, and lithium halide are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is preferably 65 to 85 mol%, more preferably 70 to 82 mol%, and even more preferably 74 to 80 mol%, from the viewpoint of obtaining higher chemical stability and higher ionic conductivity. When lithium sulfide, elemental sulfur, diphosphorus pentasulfide, lithium halide, and other raw materials used as needed are used, the content of lithium sulfide and diphosphorus pentasulfide to the total is preferably 50 to 99 mol%, more preferably 55 to 90 mol%, and even more preferably 60 to 85 mol%.

[0058] When lithium bromide and lithium iodide are used in combination as the lithium halide, from the viewpoint of improving ionic conductivity, the ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 80 mol%, even more preferably 35 to 80 mol%, and particularly preferably 45 to 70 mol%. Furthermore, when lithium bromide and lithium chloride are used in combination as the lithium halide, from the viewpoint of improving ionic conductivity, the ratio of lithium bromide to the total of lithium bromide and lithium chloride is preferably 1 to 99 mol%, more preferably 15 to 75 mol%, even more preferably 25 to 60 mol%, and particularly preferably 35 to 45 mol%.

[0059] When a halogen element is used as a raw material, and lithium sulfide, elemental sulfur, or diphosphorus pentasulfide is used, the ratio of the number of moles of lithium sulfide excluding the same number of moles of lithium sulfide as the halogen element to the total number of moles of lithium sulfide and diphosphorus pentasulfide excluding the same number of moles of lithium sulfide as the halogen element is preferably within the range of 60 to 90%, more preferably within the range of 65 to 85%, even more preferably within the range of 68 to 82%, even more preferably within the range of 72 to 78%, and particularly preferably within the range of 73 to 77%. This is because higher ionic conductivity can be obtained with these ratios. Furthermore, from the same viewpoint, when lithium sulfide, elemental sulfur, diphosphorus pentasulfide, and a halogen element are used, the content of the halogen element relative to the total amount of lithium sulfide, diphosphorus pentasulfide, and the halogen element is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, even more preferably 3 to 25 mol%, and even more preferably 3 to 15 mol%.

[0060] When lithium sulfide, elemental sulfur, diphosphorus pentasulfide, elemental halogen, and lithium halide are used, the content of elemental halogen (α mol %) and the content of lithium halide (β mol %) relative to the total amount of lithium sulfide, diphosphorus pentasulfide, elemental halogen, and lithium halide preferably satisfy the following formula (2), more preferably satisfy the following formula (3), even more preferably satisfy the following formula (4), and still more preferably satisfy the following formula (5): 2≦2α+β≦100 (2) 4≦2α+β≦80 (3) 6≦2α+β≦50 (4) 6≦2α+β≦30 (5)

[0061] When two types of halogens are used as simple substances, the molar number of one halogen atom in the substance is A1, and the molar number of the other halogen atom in the substance is A2, and the ratio A1:A2 is preferably 1 to 99:99 to 1, more preferably 10:90 to 90:10, even more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0062] When two kinds of halogen elements are used, and the two kinds of halogen elements are bromine and iodine, where A1 is the number of moles of bromine and A2 is the number of moles of iodine, A1:A2 is preferably 1:99 to 99:1, more preferably 20:80 to 80:20, even more preferably 35:65 to 80:20, and even more preferably 45:55 to 70:30. When the two kinds of halogen elements are bromine and chlorine, B1 is the number of moles of bromine and B2 is the number of moles of chlorine, and B1:B2 is preferably 1:99 to 99:1, more preferably 15:85 to 75:25, even more preferably 25:75 to 60:40, and even more preferably 35:45 to 65:55.

[0063] (Solvent) As the solvent used when mixing the raw materials, an organic solvent is preferably used, and among them, it is preferable to use a solvent containing a heteroatom.Preferably, the heteroatom contained in the solvent includes an oxygen atom, a nitrogen atom, a sulfur atom, a chlorine atom, a phosphorus atom, etc., and among them, an oxygen atom and a nitrogen atom are preferable.The solvent containing a heteroatom may contain one kind of these heteroatoms or may contain a plurality of kinds.

[0064] Examples of such heteroatom-containing solvents include oxygen-containing solvents such as alcohol solvents, ether solvents, ester solvents, aldehyde solvents, and ketone solvents; nitrogen-containing solvents such as amine solvents and nitrile solvents; and oxygen- and nitrogen-containing solvents such as amide solvents. Among these, alcohol solvents and ether solvents are preferred as oxygen-containing solvents, and nitrile solvents are preferred as nitrogen-containing solvents. The use of these solvents promotes the generation of sulfur radicals and the formation of an electrolyte precursor (polysulfide), efficiently producing a sulfide solid electrolyte with few impurities and high ionic conductivity.

[0065] These solvents may be used alone or in combination, and among the above, alcohol solvents are preferred. The use of an alcohol solvent particularly improves the effects of promoting the generation of sulfur radicals and the formation of electrolyte precursors (polysulfides). In addition, in order to improve the effects of promoting the generation of sulfur radicals and the formation of electrolyte precursors (polysulfides) in a balanced manner, it is preferred to use an alcohol solvent in combination with another solvent.

[0066] As the other solvent, it is preferable to use one solvent selected from a solvent having an oxygen atom other than an alcohol solvent and a solvent having a nitrogen atom, and as the solvent having an oxygen atom other than an alcohol solvent, an ether solvent is preferable, and as the solvent having a nitrogen atom, a nitrile solvent is preferable. That is, the solvent preferably contains an alcohol solvent and at least one organic solvent selected from an ether solvent and a nitrile solvent. In particular, it is preferable to use a combination of an alcohol solvent, an ether solvent, and a nitrile solvent. Since the generation of sulfur radicals and the formation of the electrolyte precursor (polysulfide) are promoted in a balanced manner, a sulfide solid electrolyte with few impurities and high ionic conductivity can be efficiently obtained.

[0067] (Alcohol Solvent) Examples of the alcohol solvent include aliphatic alcohols, alicyclic alcohols, heterocyclic alcohols, and aromatic alcohols. In consideration of availability and cost, aliphatic alcohols, alicyclic alcohols, and aromatic alcohols are preferred, and aliphatic alcohols are more preferred.

[0068] Representative and preferred examples of aliphatic alcohols include saturated or unsaturated monohydric aliphatic alcohols such as methanol, ethanol, various propanols, allyl alcohol, various butanols, and various buteneols; and saturated or unsaturated polyhydric aliphatic alcohols such as various propanediols, various propenediols, various butanediols, various butenediols, various hexanediols, various hexenediols, various butanetriols, erythritol, pentaerythritol, and dipentaerythritol. In this specification, "various" means that all possible isomers are included, for example, in the case of various butanols, such as 1-butanol, 2-butanol, 2-methyl-1-propanol, and 1,1-dimethylethanol. Furthermore, even if "various" is not used, compounds described in a format in which the substitution position number is not specified include all possible isomers.

[0069] The aliphatic hydrocarbon group in the aliphatic alcohol may be linear or branched, saturated or unsaturated. The number of carbon atoms in the aliphatic alcohol is preferably 1 or more, more preferably 2 or more, and is preferably 12 or less, more preferably 8 or less, and even more preferably 4 or less.

[0070] The aliphatic alcohol may be partially substituted, and preferred examples thereof include alkanolamines in which a portion of the alcohol is substituted with an amino group, such as ethanolamine, propanolamine, and dimethylethanolamine, and alcohols in which a portion of the alcohol is substituted with a halogen atom, such as fluoroalcohols.

[0071] Typical preferred examples of the alicyclic alcohol include mono- or polyhydric saturated or unsaturated monocyclic alicyclic alcohols such as cyclopropanol, methylcyclopropanol, cyclopropanemethanol, cyclobutanol, cyclobutenol, cyclopentanol, cyclopentenol, cyclohexanol, methylcyclohexanol, cyclohexenol, cyclohexanediol, and cyclohexanetriol; and mono- or polyhydric polycyclic alicyclic alcohols such as cyclopentyl cyclopentanol, cyclohexyl cyclohexanol, cyclohexylphenyl cyclohexanol, and bicyclohexanol.

[0072] The number of carbon atoms in the alicyclic alcohol is preferably 3 or more, and the upper limit is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less.

[0073] The alicyclic alcohol may be partially substituted, and preferred examples thereof include those partially substituted with saturated or unsaturated hydrocarbon groups (including linear and branched ones) such as alkyl groups and alkenyl groups, for example, those partially substituted with amino groups such as aminomethylcyclopropanol, and those partially substituted with halogen atoms. In addition, the alicyclic alcohol may be substituted with a substituent such as an amide group or a cyano group.

[0074] Typical preferred examples of heterocyclic alcohols include monocyclic heterocyclic alcohols such as oxetaneol, oxetanemethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, tetrahydropyranmethanol, morpholineethanol, and pyridinemethanol; and polycyclic condensed heterocyclic alcohols such as benzofuranmethanol and dihydrobenzofuranmethanol.

[0075] The number of carbon atoms in the heterocyclic alcohol is preferably 3 or more, and the upper limit is preferably 24 or less, more preferably 18 or less, and even more preferably 12 or less. The heterocyclic alcohol may be partially substituted, similar to the above-mentioned alicyclic alcohol.

[0076] Typical preferred examples of aromatic alcohols include monocyclic aromatic alcohols such as benzyl alcohol, salicylic alcohol, benzenedimethanol, methoxyphenylmethanol, trimethoxyphenylmethanol, and phenethyl alcohol; polycyclic aromatic alcohols such as diphenylmethanol and triphenylmethanol; and condensed polycyclic aromatic alcohols such as naphthalenemethanol, anthracenemethanol, benzofuranmethanol, and dihydrobenzofuranmethanol.

[0077] The aromatic alcohol preferably has 7 or more carbon atoms, and the upper limit is preferably 24 or less, more preferably 20 or less, and even more preferably 16 or less. The aromatic alcohol may be partially substituted, similar to the above-mentioned alicyclic alcohol.

[0078] The above examples are merely representative examples of preferred alcohol solvents, and the solvents that can be used in the production method of this embodiment are not limited to the above examples.

[0079] The alcohol solvent may be any of primary, secondary, and tertiary alcohols, preferably primary alcohols, and may also be monohydric alcohols having one hydroxyl group or polyhydric alcohols having two or more hydroxyl groups, preferably monohydric alcohols.

[0080] (Ether Solvent) Examples of the ether solvent include aliphatic ethers, alicyclic ethers, heterocyclic ethers, and aromatic ethers. In consideration of availability and cost, aliphatic ethers, alicyclic ethers, and aromatic ethers are preferred, aliphatic ethers and alicyclic ethers are more preferred, and alicyclic ethers are even more preferred.

[0081] Representative preferred examples of aliphatic ethers include monoethers such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tert-butyl methyl ether; diethers such as dimethoxymethane, dimethoxyethane, diethoxymethane, and diethoxyethane; polyethers having three or more ether groups such as diethylene glycol dimethyl ether (diglyme) and triethylene oxide glycol dimethyl ether (triglyme); and ethers containing a hydroxyl group such as diethylene glycol and triethylene glycol.

[0082] The number of carbon atoms in the aliphatic ether is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The aliphatic alcohol may be linear or branched.

[0083] Typical preferred examples of the alicyclic ether include monocyclic alicyclic ethers such as ethylene oxide, propylene oxide, furan, tetrahydrofuran, pyran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, dioxane, dioxene, dioxine, and dioxolane; and polycyclic alicyclic ethers such as dicyclopentyl ether and dicyclohexyl ether.

[0084] Representative preferred examples of heterocyclic ethers include monocyclic heterocyclic ethers such as morpholine and hydroxymethyldimethoxypyridine; and polycyclic fused heterocyclic ethers such as benzofuran, benzopyran, dibenzofuran and methoxyindole. The number of carbon atoms in the alicyclic ether or heterocyclic ether is preferably 3 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 10 or less.

[0085] Representative preferred examples of aromatic ethers include monocyclic aromatic ethers such as methyl phenyl ether (anisole) and ethyl phenyl ether; polycyclic aromatic ethers such as dibenzyl ether, diphenyl ether and benzyl phenyl ether; and condensed polycyclic aromatic ethers such as benzyl naphthyl ether and bisnaphthyl ether.

[0086] The aromatic ether preferably has 7 or more carbon atoms, more preferably 8 or more carbon atoms, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less carbon atoms.

[0087] The ether compound used in the present embodiment may be substituted with a substituent such as a linear or branched hydrocarbon group, such as an alkyl group or an alkenyl group, an alkoxyl group (the alkyl group may be linear or branched), a hydroxyl group, an amino group, an amide group or a cyano group, or a halogen atom.

[0088] Among the above ether compounds, from the viewpoint of obtaining higher ionic conductivity, alicyclic ethers are preferred, monocyclic alicyclic ethers are more preferred, and tetrahydrofuran is particularly preferred.

[0089] (Nitrile Solvent) Examples of nitrile solvents include aliphatic nitriles, alicyclic nitriles, heterocyclic nitriles, and aromatic nitriles. In view of availability and cost, aliphatic nitriles are preferred.

[0090] Typical preferred aliphatic nitriles include saturated or unsaturated aliphatic nitriles having one nitrile group, such as acetonitrile, acrylonitrile, methoxyacetonitrile, propionitrile, methoxypropionitrile, and butyronitrile; and saturated or unsaturated aliphatic nitriles having two or more nitrile groups, such as propanedinitrile, propanetricarbonitrile, butanedinitrile, butenedinitrile, butanetricarbonitrile, pentanedinitrile, pentanetricarbonitrile, hexanedinitrile, hexenedinitrile, hexanetricarbonitrile, and methylenepentanedinitrile.

[0091] The number of carbon atoms in the aliphatic nitrile is preferably 2 or more, and the upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less. The number of carbon atoms in the aliphatic hydrocarbon group in the aliphatic nitrile is preferably 1 or more, and the upper limit is preferably 8 or less, more preferably 6 or less, and even more preferably 2 or less. The aliphatic hydrocarbon group in the aliphatic nitrile may be linear or branched.

[0092] Typical preferred examples of the alicyclic nitrile include monocyclic or polycyclic alicyclic nitriles having one nitrile group, such as cyanocyclopropane, cyclobutanecarbonitrile, hydroxycyclobutanecarbonitrile, oxocyclobutanecarbonitrile, cyclopentanecarbonitrile, furancarbonitrile, tetrahydropyrancarbonitrile, cyclohexanecarbonitrile, and bicyclobutanecarbonitrile; and alicyclic nitriles having two or more nitrile groups, such as furandicarbonitrile, cyclobutanedicarbonitrile, cyclopentanedicarbonitrile, cyclohexanedicarbonitrile, and cyclohexanetricarbonitrile.

[0093] Typical preferred examples of the heterocyclic nitrile include monocyclic heterocyclic nitriles having one or more nitrile groups, such as morpholinecarbonitrile, tetrahydrofurfurylcarbonitrile, cyanopyridine, pyridinedicarbonitrile, pyridinetricarbonitrile, and furfurylmalononitrile; and polycyclic or polycyclic condensed heterocyclic nitriles having one or more nitrile groups, such as benzofurancarbonitrile, dibenzofurandicarbonitrile, and dicyanobipyridine.

[0094] The number of carbon atoms in the alicyclic nitrile and heterocyclic nitrile is preferably 3 or more, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 10 or less.

[0095] Typical preferred examples of aromatic nitriles include monocyclic aromatic nitriles having one or more nitrile groups, such as phenylacetonitrile, cyanotoluene, benzonitrile, benzenedicarbonitrile, and benzenetricarbonitrile; and polycyclic or condensed polycyclic aromatic nitriles having one or more nitrile groups, such as biphenyldicarbonitrile, phenylcyclobutanecarbonitrile, naphthalenecarbonitrile, naphthalenedicarbonitrile, naphthalenetricarbonitrile, anthracenecarbonitrile, and cyclopentylbenzonitrile.

[0096] The aromatic nitrile preferably has 7 or more carbon atoms, more preferably 8 or more carbon atoms, and the upper limit is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less carbon atoms.

[0097] The ether compound used in the present embodiment may be substituted with a substituent such as a linear or branched hydrocarbon group, such as an alkyl group or an alkenyl group, an alkoxyl group (the alkyl group may be linear or branched), a hydroxyl group, an amino group, an amide group or a cyano group, or a halogen atom.

[0098] (Other Solvents Having Heteroatoms) Preferred examples of the amine solvents and amide solvents exemplified as solvents having heteroatoms other than the alcohol solvents, ether solvents, and nitrile solvents include heterocyclic aromatic amine solvents such as pyridine; and amide solvents such as dimethylformamide, dimethylacetamide, hexamethylphosphoramide, and N-methylpyrrolidone.

[0099] (Other Solvents) In the production method of this embodiment, other solvents may be used in addition to the above-mentioned solvents, such as aliphatic hydrocarbon solvents such as hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, and tert-butylbenzene.

[0100] In this case, the smaller the amount of the other solvent used, the better, for example, it is preferably 50.0 parts by volume or less, more preferably 30.0 parts by volume or less, and even more preferably 15.0 parts by volume or less, relative to 100.0 parts by volume of the solvent (i.e., the solvent containing a heteroatom). Of course, it is preferable to use only the above-mentioned solvent (i.e., the solvent containing a heteroatom) without using any other solvent.

[0101] (Amount of Solvent Used) In the production method of the present embodiment, when an alcohol solvent is used, the amount of the alcohol solvent used is preferably 0.005 mol or more, more preferably 0.010 mol or more, even more preferably 0.015 mol or more, and still more preferably 0.020 mol or more, relative to 1.0 mol of lithium sulfide used as a raw material, and the upper limit is preferably 20.0 mol or less, more preferably 16.0 mol or less, and even more preferably 10.0 mol or less.

[0102] Furthermore, when at least one organic solvent selected from alcohol solvents, ether solvents, and nitrile solvents is used, and an alcohol solvent is used, the total amount of the ether solvent and the nitrile solvent used is preferably 2.0 parts by volume or more, more preferably 5.0 parts by volume or more, even more preferably 15.0 parts by volume or more, still more preferably 50.0 parts by volume or more, and particularly preferably 150.0 parts by volume or more, relative to 1.0 part by volume of the alcohol solvent used, and the upper limit is preferably 10,000.0 parts by volume or less, more preferably 9,000.0 parts by volume or less, even more preferably 8,000.0 parts by volume or less, and still more preferably 7,800.0 parts by volume or less.

[0103] (Mixing) In the production method of this embodiment, raw material contents including raw materials are mixed in the solvent. By mixing the raw material contents in the solvent, the generation of sulfur radicals and the formation of an electrolyte precursor are promoted, and a sulfide solid electrolyte with few impurities and high ionic conductivity can be efficiently obtained.

[0104] There are no particular limitations on the method for mixing the raw material ingredients in the solvent; the raw material ingredients can be mixed by simply adding the solvent and raw material ingredients to a device capable of mixing the raw material ingredients in the solvent. For example, it is preferable to supply the solvent into a tank, operate the stirring blade, and then gradually add the raw material ingredients. It is also preferable to supply the raw material ingredients into a tank, operate the stirring blade, and then gradually add the solvent. Since a good mixing state of the raw material ingredients is obtained, the dispersion of the raw material ingredients is improved, and the generation of sulfur radicals and the formation of electrolyte precursors (polysulfides) are promoted. However, when using a halogen element as a raw material, the raw material may not be solid. Specifically, at room temperature and normal pressure, fluorine and chlorine are gases, and bromine is liquid. In such cases, for example, if the raw material is liquid, it can be supplied into the tank together with the solvent separately from other solid raw materials. Alternatively, if the raw material is gas, it can be supplied by blowing it into the solvent containing the solid raw material.

[0105] There are no particular restrictions on the order in which the raw materials of the raw material content are added and mixed, but in consideration of work efficiency, it is preferable to mix all the raw materials at the same time, that is, all at once.

[0106] Furthermore, in order to improve the solubility of the raw materials, further suppress the generation of impurities, and more efficiently obtain a sulfide solid electrolyte having high ionic conductivity, it is preferable to perform split mixing in which the raw materials are divided into two raw material groups, raw material group 1 and 2, and raw material group 1 is mixed first and then raw material group 2 is mixed.

[0107] When performing split mixing, as described above, raw material group 1 preferably contains elemental sulfur. This promotes the formation of sulfur radicals, allowing a sulfide solid electrolyte with high ionic conductivity to be obtained more efficiently. From a similar perspective, as described above, a combination of raw material group 1 containing a raw material containing at least one atom selected from lithium atoms, phosphorus atoms, and sulfur atoms, elemental sulfur, and lithium sulfide, and raw material group 2 containing a raw material containing a halogen atom is preferred. This is because raw material group 1 contains elemental sulfur and lithium sulfide, and the reaction between these promotes the formation of sulfur radicals via lithium polysulfides. From a similar perspective, a combination of raw material group 1 containing a raw material containing a halogen atom, elemental sulfur, and lithium sulfide, and raw material group 2 containing a raw material containing a phosphorus atom and sulfur atom is also preferred.

[0108] In the production method of this embodiment, the order in which the raw materials are charged and mixed may be selected depending on whether importance is attached to work efficiency or to the ionic conductivity of the sulfide solid electrolyte.

[0109] As described above, in the manufacturing method of this embodiment, the raw material contained in the raw material content is PS ４ Li containing structure ３ P.S. ４ can be prepared in advance by production or the like and used. ３ P.S. ４ can be produced by blending, for example, lithium sulfide and diphosphorus pentasulfide in a molar ratio of 75:25. In the production method of this embodiment, when diphosphorus pentasulfide is used in addition to lithium sulfide as raw materials, a raw material group 1 containing lithium sulfide and diphosphorus pentasulfide in a predetermined molar ratio, such as 75:25, and containing elemental sulfur, can be mixed in a solvent, and then a raw material group 2 containing a raw material containing a halogen atom, such as lithium halide, and other remaining raw materials required for producing the desired sulfide solid electrolyte, for example, a raw material group containing the shortage of lithium sulfide, can be added and mixed. ３ P.S. ４A sulfide solid electrolyte can be obtained more efficiently by forming an electrolyte precursor (polysulfide) containing the basic structure of

[0043] . Here, the predetermined molar ratio of lithium sulfide to diphosphorus pentasulfide is preferably 55-85:15-45, more preferably 60-80:20-40, and even more preferably 65-75:25-35.

[0110] The manufacturing method of this embodiment is characterized by including mixing of raw material ingredients in a solvent. That is, since the raw material ingredients only need to be mixed and not pulverized, the solid electrolyte can be manufactured without using equipment commonly referred to as a pulverizer, such as a media-type pulverizer such as a ball mill or a bead mill, which is typically used for pulverizing solid electrolyte raw materials. In the manufacturing method of this embodiment, simply mixing the raw material ingredients in a solvent mixes the solvent and raw materials, generating polysulfides, which serve as electrolyte precursors. When these polysulfides are decomposed by heating or the like, an amorphous sulfide solid electrolyte, or even a crystalline sulfide solid electrolyte, can be formed. The raw material mixture in the solvent may be pulverized using a pulverizer to shorten the mixing time or to achieve finer powder to obtain the electrolyte precursor. However, as previously mentioned, it is preferable not to use a pulverizer.

[0111] An example of an apparatus for mixing the raw material ingredients in a solvent is a mechanical agitation mixer equipped with an agitator blade in a tank. Examples of mechanical agitation mixers include high-speed agitation mixers and double-arm mixers, and high-speed agitation mixers are preferably used from the viewpoint of increasing the uniformity of the raw materials in the mixture of raw material ingredients and obtaining higher ionic conductivity. Examples of high-speed agitation mixers include vertical-axis rotary mixers and horizontal-axis rotary mixers, and either type of mixer may be used.

[0112] Examples of the shape of the impeller used in a mechanical stirring 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-type blade type, etc., and from the viewpoint of improving the uniformity of the solid electrolyte raw material and obtaining higher ionic conductivity, the shovel type, flat blade type, C-type blade type, etc. are preferred. Furthermore, in a mechanical stirring mixer, it is preferable to install a circulation line that discharges the material to be stirred outside the mixer and then returns it to the mixer. This allows raw materials with a high specific gravity, such as lithium halide, to be stirred without settling or stagnation, enabling more uniform mixing.

[0113] The location of the circulation line is not particularly limited, but it is preferably installed at a location where it discharges from the bottom of the mixer and returns to the top of the mixer. This makes it easier to uniformly mix the solid electrolyte raw material, which tends to settle, by using convection caused by circulation. Furthermore, it is preferable that the return port is located below the liquid surface of the material to be mixed. This can prevent the material to be mixed from splashing and adhering to the wall surfaces inside the mixer.

[0114] The mixing time when mixing the raw material ingredients in the solvent is not particularly limited as an upper limit, but in consideration of efficiency, it is preferably 240 minutes or less, more preferably 60 minutes or less, even more preferably 30 minutes or less, and even more preferably 15 minutes or less, and the lower limit is usually 0.1 minutes or more, preferably 1 minute or more, and even more preferably 3 minutes or more. In addition, the temperature conditions when mixing the raw material ingredients in the solvent are not particularly limited, and are, for example, −30 to 100° C., preferably −10 to 50° C., and more preferably about room temperature (23° C.) (for example, about room temperature ±5° C.).

[0115] [Heating] The production method of this embodiment includes heating after mixing the raw material components. Heating can decompose the generated polysulfides, remove the solvent, and remove and crystallize elemental sulfur generated by decomposition of the polysulfides. Furthermore, elemental sulfur can also be removed by heating, but other methods such as solvent washing and hydrodesulfurization may be used to remove elemental sulfur.

[0116] The heating temperature is not particularly limited as long as it is equal to or higher than room temperature, and although it cannot be generally determined because room temperature may vary, it is usually preferably equal to or higher than 20° C., with the upper limit preferably equal to or lower than 500° C. If the heating temperature is within the above range, decomposition of polysulfides, removal of the solvent and removal of elemental sulfur, as well as crystallization can be more efficiently carried out.

[0117] For example, it is preferable to perform heating (first heating) mainly for decomposing the produced polysulfides, removing the solvent, and removing elemental sulfur, followed by heating (second heating) for crystallization. More specifically, it is preferable to perform the first heating at a heating temperature of 20° C. or higher but lower than 150° C. and the second heating at a heating temperature of 150° C. or higher but 500° C. or lower.

[0118] The heating temperature in the first heating may be 20°C or higher and lower than 150°C. For example, heating at a lower temperature may be followed by heating at a higher temperature; that is, the first heating may be performed by further multi-stage heating. Typically, solvent removal begins at 20°C or higher, decomposition of polysulfides begins at 60°C or higher, and sulfur removal begins at 100°C or higher. By performing multi-stage heating at heating temperatures appropriate for these purposes, each purpose can be achieved more efficiently, making it easier to obtain a sulfide solid electrolyte with improved ionic conductivity. In particular, by reliably removing elemental sulfur, the generation of impurities due to remaining elemental sulfur can be further suppressed, making it easier to obtain a sulfide solid electrolyte with improved ionic conductivity.

[0119] For example, when heating at a lower temperature (first heating-1), the heating temperature is preferably 20°C or higher, with the upper limit preferably being less than 60°C, more preferably being 50°C or lower. By setting the temperature range in this way, it becomes possible to remove the solvent. Next, when heating at a higher temperature (first heating-2), the heating temperature is preferably 60°C or higher, more preferably 65°C or higher, even more preferably 75°C or higher, still more preferably 95°C or higher, and particularly preferably 110°C or higher, with the upper limit being less than 150°C, more preferably 145°C or lower, even more preferably 135°C or lower, and still more preferably 130°C or lower. By setting the temperature range in this way, it becomes possible to mainly decompose polysulfides and remove sulfur.

[0120] As for the first heating, as described above, depending on the heating temperature, either solvent removal, decomposition of polysulfides, or sulfur removal can be performed. Therefore, various embodiments can be taken by adjusting the heating temperature. For example, if the heating temperature of the first heating is 60°C or higher (less than 100°C), it is possible to remove the solvent and decompose the polysulfides. This is referred to as first heating-1, and by performing heating at 100°C or higher (less than 150°C) as first heating-2, it is possible to remove sulfur. In this case, first heating-2 is not performed, and as described above, sulfur removal can be performed by a method other than heating, i.e., solvent washing, hydrodesulfurization, etc., and then second heating can be performed. Methods for removing sulfur, such as solvent washing and hydrodesulfurization, will be described later.

[0121] Furthermore, for example, if the heating temperature of the first heating is set to 20°C or higher (less than 60°C), the solvent can be removed, and this is designated as First Heating-1. If First Heating-2 is heated at 60°C or higher (less than 100°C), the polysulfides can be decomposed, and then First Heating-3 is heated at 100°C or higher (less than 150°C) to remove sulfur. In this case, three-stage heating can be performed. In place of First Heating-3, sulfur can be removed by a method other than heating, as described above. Also, by setting the heating temperature of First Heating-2 to 100°C or higher (less than 150°C), decomposition of polysulfides and removal of sulfur can be performed simultaneously.

[0122] The above has described the case where the first heating is performed by multi-stage heating. However, if the heating temperature of the first heating is set to 100°C or higher, for example, removal of the solvent, decomposition of polysulfides, and removal of sulfur can be performed, and therefore multi-stage heating is not necessary.

[0123] The heating time of the first heating is not particularly limited as long as it is at least long enough to remove the solvent, but is, for example, preferably 10 minutes or more, more preferably 30 minutes or more, even more preferably 45 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0124] The pressure conditions during the first heating are preferably normal pressure or reduced pressure. When reduced pressure is used, specifically, the pressure is preferably 85 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa or less. The lower limit may be a vacuum (0 kPa). 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.

[0125] Furthermore, the heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). For example, an inert gas atmosphere containing a certain concentration of hydrogen may be used. This is because deterioration (e.g., oxidation) of the sulfide solid electrolyte can be prevented.

[0126] The heating temperature in the second heating cannot be generally determined because it varies depending on the sulfide solid electrolyte to be produced. However, taking into consideration the relationship with the first heating, the heating temperature is sufficient as long as it is 150°C or higher and 500°C or lower, preferably 160°C or higher, more preferably 200°C or higher, and even more preferably 240°C or higher, with the upper limit being preferably 480°C or lower, more preferably 460°C or lower, and even more preferably 440°C or lower.

[0127] The second heating may also be performed in multiple stages, similar to the first heating. Performing multiple stages as the second heating can ensure more reliable crystallization. When performing multiple stages of heating, for example, the heating temperature at a lower heating temperature (second heating-1) is preferably 150°C or higher but lower than 270°C, and the heating temperature at a higher heating temperature (second heating-2) is preferably 270°C or higher but 500°C. The lower limit of second heating-1 is preferably the lower limit temperature of the second heating, and the upper limit is preferably 265°C or lower, more preferably 255°C or lower. The upper limit of second heating-2 is preferably the upper limit temperature of the second heating, and the lower limit is preferably 290°C or higher, more preferably 340°C or higher, and even more preferably 375°C or higher.

[0128] The heating time and pressure conditions in the second heating are the same as those in the first heating, and it is also preferable that the heating is performed in an inert gas atmosphere.

[0129] The heating method is not particularly limited, and examples thereof include methods using various heating devices such as a hot plate, a vacuum heating device, an argon gas atmosphere furnace, a baking furnace, a vacuum baking furnace, etc. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feeding mechanism can also be used, and the method may be selected depending on the amount of processing to be heated.

[0130] (Sulfur Removal) In the production method of this embodiment, sulfur may be removed by a method other than heating as described above. For example, when the first heating is performed at a temperature of less than 100°C, sulfur is preferably removed by a method other than heating. Examples of the method for removing sulfur include solvent washing and hydrodesulfurization.

[0131] The solvent washing method is a method in which the powder that has been subjected to the first heating is washed with a solvent that dissolves sulfur, such as an aromatic hydrocarbon solvent such as benzene, toluene, or xylene; or a sulfur-containing organic solvent such as carbon disulfide, to remove sulfur.

[0132] The hydrodesulfurization method involves mixing the powder that has been subjected to the first heating with a hydrodesulfurization catalyst, and passing hydrogen through the mixture while heating at 300 to 450° C., thereby removing sulfur through a hydrodesulfurization reaction. Preferred examples of the hydrodesulfurization catalyst include porous catalysts containing nickel, molybdenum, cobalt, tungsten, or the like as active metal elements, such as NiMo catalysts, CoMo catalysts, and NiW catalysts.

[0133] (Amorphous sulfide solid electrolyte) In the production method of the present embodiment, an amorphous sulfide solid electrolyte is produced by mixing the raw material ingredients described above or by performing the first heating step described above mainly for removing the solvent.

[0134] The amorphous sulfide solid electrolyte produced by the manufacturing method of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and representative examples thereof include Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -LiI-LiBr, etc., solid electrolytes composed of lithium sulfide, phosphorus sulfide, and lithium halide; and solid electrolytes further containing other atoms such as oxygen atoms and silicon atoms, for example, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ -P ２ S ５ In order to obtain higher ionic conductivity, a solid electrolyte such as Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li２ S-P ２ S ５ A solid electrolyte composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as LiI-LiBr, is preferred. The types of atoms constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0135] The amorphous sulfide solid electrolyte produced in the manufacturing method of this embodiment contains at least Li ２ S-P ２ S ５ When Li ２ S and P ２ S ５ From the viewpoint of obtaining higher ionic conductivity, the molar ratio of 65-85:15-35 is preferred, 70-82:18-30 is more preferred, and 74-80:20-26 is even more preferred.

[0136] The amorphous sulfide solid electrolyte produced in the manufacturing method of this embodiment is, for example, Li ２ S-P ２ S ５ In the case of -LiI-LiBr, the total content of lithium sulfide and diphosphorus pentasulfide is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. The ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, even more preferably 40 to 75 mol%, and particularly preferably 45 to 60 mol%. In addition, the amorphous sulfide solid electrolyte produced by the production method of this embodiment may be, for example, Li ２ S-P ２ S ５ In the case of -LiCl-LiBr, the total content of lithium sulfide and diphosphorus pentasulfide is preferably 45 to 80 mol%, more preferably 50 to 75 mol%, and even more preferably 55 to 70 mol%. The ratio of lithium bromide to the total content of lithium bromide and lithium chloride is preferably 1 to 99 mol%, more preferably 15 to 75 mol%, even more preferably 25 to 60 mol%, and particularly preferably 35 to 45 mol%.

[0137] The shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle size (D ５０ ) is, for example, 0.01 μm or more, further 0.03 μm or more, 0.05 μm or more, or 0.1 μm or more, and the upper limit is 200.0 μm or less, further 100.0 μm or less, 10.0 μm or less, 1.0 μm or less, or 0.5 μm or less.

[0138] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may be a so-called glass ceramic obtained by heating an amorphous sulfide solid electrolyte to a crystallization temperature or higher, and its crystalline structure may be Li ３ P.S. ４ Crystal structure, Li ４ P ２ S ６ Crystal structure, Li ７ P.S. ６ Crystal structure, Li ７ P ３ S １１ Examples of such structures include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0139] Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li ４－ｘ Ge １－ｘ P ｘ S ４Examples of the crystal structure include a crystal structure similar to the thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). The crystal structure of the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment is preferably the thio-LISICON Region II type crystal structure among the above, in that higher ionic conductivity can be obtained. Here, the "thio-LISICON Region II type crystal structure" refers to a crystal structure in which Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４ This indicates that the thio-LISICON region II type has a similar crystal structure to the thio-LISICON region II type.

[0140] The crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment may contain the above-mentioned thiolicon region II type crystal structure or may contain it as the main crystal, but from the viewpoint of obtaining higher ionic conductivity, it is preferable that it contains it as the main crystal. In this specification, "containing it as the main crystal" means that the proportion of the target crystal structure among the crystal structures is 80% or more, preferably 90% or more, and more preferably 95% or more. Furthermore, from the viewpoint of obtaining higher ionic conductivity, the crystalline sulfide solid electrolyte obtained by the manufacturing method of this embodiment contains crystalline Li ３ P.S. ４ (β-Li ３ P.S. ４ ) is preferably not included.

[0141] In X-ray diffraction measurement using CuKα radiation, Li ３ P.S. ４ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.5°, 18.3°, 26.1°, 27.3°, and 30.0°. ４ P ２ S ６Diffraction peaks of the crystal structure appear, for example, at 2θ=16.9°, 27.1°, and 32.5°. ７ P.S. ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=15.3°, 25.2°, 29.6°, and 31.0°. ７ P ３ S １１ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ The diffraction peaks of the thio-LISICON Region II crystal structure appear, for example, at 2θ=20.1°, 23.9°, and 29.5°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ Diffraction peaks of a crystal structure similar to that of thio-LISICON Region II type appear, for example, at 2θ=20.2° and 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0142] The above Li ７ P.S. ６ A preferred example of the crystalline sulfide solid electrolyte is an argyrodite-type crystal structure having a structural skeleton in which part of P is substituted with Si. The composition formula of the argyrodite-type crystal structure is, for example, the composition formula Li ７－ｘ P １－ｙ Si ｙ S ６ and Li ７＋ｘ P １－ｙ Si ｙ S ６ (x is −0.6 to 0.6, y is 0.1 to 0.6) The argyrodite-type crystal structure represented by this composition formula is a cubic or orthorhombic crystal, preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°.

[0143] The composition formula of the argyrodite-type crystal structure is Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦−0.25x+0.5) is also included. The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, has peaks that appear mainly at 2θ=15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. The composition formula of the argyrodite-type crystal structure is preferably the composition formula Li ７－ｘ P.S. ６－ｘ Ha ｘ (Ha is Cl or Br, and x is preferably 0.2 to 1.8). The argyrodite-type crystal structure represented by this composition formula is preferably a cubic crystal, and in X-ray diffraction measurement using CuKα radiation, it has peaks that appear mainly at 2θ = 15.5°, 18.0°, 25.0°, 30.0°, 31.4°, 45.3°, 47.0°, and 52.0°. Note that these peak positions may vary within a range of ±0.5°.

[0144] The shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) is, for example, 0.01 μm or more, further 0.03 μm or more, 0.05 μm or more, or 0.1 μm or more, and the upper limit is 200.0 μm or less, further 100.0 μm or less, 10.0 μm or less, 1.0 μm or less, or 0.5 μm or less.

[0145] (Applications) The sulfide solid electrolyte obtained by the manufacturing method of this embodiment has high ionic conductivity and excellent battery performance, and is therefore suitable for use in batteries. The sulfide solid electrolyte obtained by the manufacturing method of this embodiment may be used in a positive electrode layer, a negative electrode layer, or an electrolyte layer. Each layer may be manufactured by a known method.

[0146] The battery preferably includes a current collector in addition to the positive electrode layer, the electrolyte layer, and the negative electrode layer, and a known current collector can be used. For example, 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.

[0147] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0148] (Measurement of Powder XRD Diffraction) Powder X-ray diffraction (XRD) measurement was carried out as follows. The sulfide solid electrolyte powder obtained in the Examples and Comparative Examples was filled into a groove 20 mm in diameter and 0.2 mm deep, and leveled with glass to prepare a sample. This sample was sealed with Kapton film for XRD and measured under the following conditions without being exposed to air. Measurement device: D2 PHASER, manufactured by Bruker Corporation Tube voltage: 30 kV Tube current: 10 mA X-ray wavelength: Cu-Kα ray (1.5418 Å) Optical system: focusing method Slit configuration: Soller slit 4°, divergence slit 1 mm, Kβ filter (Ni plate) used Detector: semiconductor detector Measurement range: 2θ = 10-60 deg Step width, scan speed: 0.05 deg, 0.05 deg / sec

[0149] (Measurement of Ion Conductivity) In the present example, the measurement of ion conductivity was carried out as follows. A 10 mm diameter (cross-sectional area S: 0.785 cm ) sample was taken from the crystalline sulfide solid electrolyte obtained in the examples and comparative examples. ２ ), and a height (L) of 0.1 to 0.3 cm were molded into a circular pellet to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C using an AC impedance method (frequency range: 5 MHz to 0.5 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following formula: R = ρ (L / S) σ = 1 / ρ

[0150] Example 1 In a glove box under an argon atmosphere, 0.2546 g of lithium sulfide, 0.3241 g of diphosphorus pentasulfide, and 0.3554 g of elemental sulfur were mixed using a mortar and introduced into a 100 mL reaction vessel (Reaction Vessel 1) together with a stirrer. Similarly, 0.1236 g of lithium chloride and 0.1520 g of lithium bromide were mixed using a mortar and introduced into another 100 mL reaction vessel (Reaction Vessel 2) together with a stirrer. Under a nitrogen atmosphere, 60 mL of a mixed solvent of ethanol (EtOH), tetrahydrofuran (THF), and acetonitrile (ACN) (the total amount of tetrahydrofuran (THF) and acetonitrile (ACN) was 40.1 parts by volume relative to 1.0 part by volume of ethanol (EtOH); the volume ratio of ethanol:tetrahydrofuran:acetonitrile was 0.050:1:1) was added to Reaction Vessel 1, and the mixture was stirred for 10 minutes using a magnetic stirrer. Next, the solution from reaction vessel 1 was added to reaction vessel 2, and further mixing was carried out by stirring with a magnetic stirrer for 10 minutes. Next, using a vacuum pump and an oil bath, heating was carried out at room temperature (20°C) under reduced pressure for 1 hour (first heating-1), and then at 130°C under reduced pressure for 1 hour (first heating-2). Furthermore, the powder obtained in the first heating was heated at 250°C in an argon atmosphere for 1 hour (second heating-1), and further heated at 430°C in a nitrogen atmosphere for 8 hours (second heating-2), to obtain a powder.

[0151] Powder XRD diffraction measurements were performed on the powders obtained by the first heating at room temperature (20°C) and 130°C and the second heating at 250°C and 430°C. The X-ray diffraction spectra of the powder obtained by heating at 130°C are shown in Figures 1 and 4, the X-ray diffraction spectra of the powder obtained by heating at 250°C are shown in Figures 2 and 5, and the X-ray diffraction spectra of the powder obtained by heating at 430°C are shown in Figures 3 and 6. In addition, the ionic conductivity of the powder obtained by heating at 430°C in Example 1 was measured and found to be 4.8 mS / cm.

[0152] (Examples 2, 3, 4, and 7) Powders of Examples 2, 3, 4, and 7 were obtained in the same manner as in Example 1, except that the composition ratio and supply amount of the solvent in Example 1 were set as shown in Table 1A. Powder XRD diffraction measurements were performed on the powders obtained in Examples 2, 3, 4, and 7. X-ray diffraction spectra of the powders obtained by heating at 130°C in Examples 2, 3, and 4 are shown in Figure 1, X-ray diffraction spectra of the powders obtained by heating at 250°C in Examples 2, 3, and 4 are shown in Figure 2, X-ray diffraction spectra of the powders obtained by heating at 430°C in Examples 2, 3, and 4 are shown in Figures 10, 11, and 12, respectively. In addition, the ionic conductivity of the powders obtained by heating at 430°C in Examples 2, 3, 4, and 7 was measured. The results are shown in Table 1A.

[0153] Example 5 A powder was obtained in the same manner as in Example 2, except that all the raw materials were simultaneously mixed in a mortar and introduced into a reaction vessel, and mixed with the solvent by stirring for 10 minutes.

[0154] Example 6 A powder was obtained in the same manner as in Example 2, except that 0.1236 g of lithium chloride, 0.1520 g of lithium bromide, 0.2546 g of lithium sulfide, and 0.3554 g of sulfur were introduced into a reaction vessel, and mixed with the solvent by stirring for 10 minutes (reaction vessel 1), and then the solution in reaction vessel 1 was added to reaction vessel 2, into which 0.3241 g of diphosphorus pentasulfide had been introduced, and mixed by stirring for 10 minutes.

[0155] The X-ray diffraction spectra of the powders obtained by heating at 130°C in Examples 2, 5, and 6 are shown in Figure 7, the X-ray diffraction spectra of the powders obtained by heating at 250°C in Examples 2, 5, and 6 are shown in Figure 8, and the X-ray diffraction spectra of the powders obtained by heating at 430°C in Examples 2, 5, and 6 are shown in Figure 9. The ionic conductivity of the powders obtained by heating at 430°C in Examples 5 and 6 was also measured. The results are shown in Table 1A.

[0156] Comparative Examples 1 and 2 Powders of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the amount of elemental sulfur used was changed from 0.3544 g to 0.1269 g and 0.1777 g, respectively.

[0157] The X-ray diffraction spectra of the powders obtained by heating at 130°C in Comparative Examples 1 and 2 are shown in Figure 4, the X-ray diffraction spectra of the powders obtained by heating at 250°C in Comparative Examples 1 and 2 are shown in Figure 5, and the X-ray diffraction spectra of the powders obtained by heating at 430°C in Comparative Examples 1 and 2 are shown in Figure 6. In addition, the ionic conductivity of the powders obtained by heating at 430°C in Comparative Examples 1 and 2 was measured. The results are shown in Table 1A.

[0158] *1. Raw material supply methods A to C are as follows. A: Lithium sulfide, diphosphorus pentasulfide, and elemental sulfur were mixed, followed by lithium chloride and lithium bromide. B: Lithium sulfide, diphosphorus pentasulfide, elemental sulfur, lithium chloride, and lithium bromide were mixed simultaneously. C: Lithium chloride, lithium bromide, lithium sulfide, and elemental sulfur were mixed, followed by diphosphorus pentasulfide.

[0159] Examples 8 to 11 The powder of Example 8 was obtained in the same manner as Example 1, except that the amount of sulfur atoms used, the composition ratio of the solvent, and the supply rate were set according to the conditions shown in Table 1B. Furthermore, the powders of Examples 9 to 11 were obtained in the same manner as Example 1, except that the composition ratio of the solvent and the supply rate were set according to the conditions shown in Table 1B. Powder XRD diffraction measurements were performed on the powders obtained in Examples 8 to 11. X-ray diffraction spectra of the powders obtained by heating at 130°C, 250°C, and 430°C in Example 8 are shown in Figures 15 to 17 (the X-ray diffraction spectra in these figures also show those of Example 1, Comparative Examples 1, and 2). X-ray diffraction spectra of the powders obtained by heating at 130°C, 250°C, and 430°C in Examples 9 to 11 are shown in Figures 18 to 20 (the X-ray diffraction spectra in these figures also show those of Example 2). Furthermore, the ionic conductivity of the powders obtained by heating at 430°C in Examples 8 to 11 was measured. The results are shown in Table 1B.

[0160]

[0161] As shown in Figures 2, 3, 5, 6, 8, 9, 11, and 12, the powders obtained by heating at 250 ° C. and 430 ° C. in Examples 1 to 7 had peaks at 2θ = 15.5 °, 18.0 °, 25.0 °, 30.0 °, 31.4 °, 45.3 °, 47.0 °, and 52.0 °, confirming that they were crystalline sulfide solid electrolytes having an argyrodite-type crystal structure. Furthermore, as shown in Figures 16, 17, 19, and 20, the powders obtained by heating at 250 ° C. and 430 ° C. in Examples 8 to 11 were also confirmed to be crystalline sulfide solid electrolytes having an argyrodite-type crystal structure, as in Examples 1 to 7.

[0162] As shown in Figures 1, 4, 7, and 10, and Figures 15 and 18, for the powders obtained by heating at 130°C in Examples 1 to 7 and the powders obtained by heating at 130°C in Examples 8 to 11, although some impurity peaks were observed, peaks attributable to the argyrodite-type crystal structure were confirmed, confirming that the powders were crystalline sulfide solid electrolytes having the argyrodite-type crystal structure. In Examples 5 and 6, a peak believed to be attributable to lithium sulfide was observed at 2θ = 27.0°, and in Examples 1, 2, 5, 6, and 7, a peak believed to be attributable to lithium chloride was observed at 2θ = 34.9°. It was also found that the peak intensity attributable to the argyrodite-type crystal structure was weaker than the peak intensity of the crystalline sulfide solid electrolyte after heating at 250°C and 430°C. From a comparison of FIGS. 3, 6, 9, and 12 with FIGS. 1, 4, 7, and 10, it was confirmed that by performing heating at a higher heating temperature (heating corresponding to the second heating), peaks due to raw materials such as lithium sulfide and lithium chloride were no longer observed and the crystallinity was improved.

[0163] As shown in FIG. 3, the powders obtained by heating at 430° C. in Examples 3 and 4 have a P value of 2θ=22.1° and 23.0°, which is higher than that of the powders in Examples 1 and 2. ２ O ５The peak intensity due to the oxygen in the ethanol was small, while the peak intensity due to the argyrodite-type crystal structure was large. It is believed that the small amount of alcohol solvent (ethanol) in the solvent suppressed the generation of oxides derived from oxygen in the ethanol, improving the crystallinity of the crystalline sulfide solid electrolyte having the argyrodite-type crystal structure. The ionic conductivities of the powders of Examples 1, 2, 3, and 4 were 4.8 mS / cm, 5.3 mS / cm, 6.7 mS / cm, and 8.4 mS / cm, respectively, and the smaller the amount of ethanol in the solvent and the smaller the amount of alcohol solvent (ethanol) used relative to lithium sulfide, the higher the conductivity obtained.

[0164] As shown in FIG. 7 , in the powders obtained by heating at 130°C in Examples 2, 5, and 6, only in Examples 5 and 6 was a peak at 2θ = 27.0° that appeared to be due to lithium sulfide confirmed. This indicates that, although it is possible to obtain a crystalline sulfide solid electrolyte having an argyrodite-type crystal structure regardless of the raw material supply method, supply method A most efficiently promotes the reaction. As shown in FIG. 9 , in the powders obtained by heating at 430°C in Examples 5 and 6, which were supplied by a method other than supply method A, the reaction progressed due to heating, and the peak due to lithium sulfide disappeared. However, for example, the ionic conductivities of the powders in Examples 2, 5, and 6 were 5.3 mS / cm, 4.3 mS / cm, and 4.3 mS / cm, respectively, indicating that supply method A provided the highest ionic conductivity.

[0165] From the above results, it was confirmed that, although a sulfide solid electrolyte having sufficiently high ionic conductivity can be obtained by any of the supply methods, in order to obtain a higher ionic conductivity, it is more effective to supply the raw materials in separate supply into raw material groups 1 and 2 rather than mixing the raw materials all at once, in particular to supply the raw materials in separate supply into raw material group 1 containing a raw material containing at least one atom selected from lithium atoms, phosphorus atoms, and sulfur atoms, elemental sulfur, and lithium sulfide, and raw material group 2 containing a raw material containing a halogen atom.

[0166] As shown in Figures 4 and 5, the powders obtained by heating at 130 °C and 250 °C in Comparative Examples 1 and 2 exhibited peaks attributable to the argyrodite-type crystal structure, similar to the powder in Example 1. However, a large peak at 2θ = 27.0 °C attributable to lithium sulfide was also observed, indicating that the reaction did not proceed efficiently. As shown in Figure 6, in the powders obtained by heating at 430 °C in Comparative Examples 1 and 2, the reaction proceeded with heating, and the peak attributable to lithium sulfide disappeared. However, for example, the ionic conductivities of the powders in Example 1, Comparative Examples 1, and 2 were 4.8 mS / cm, 3.5 mS / cm, and 3.6 mS / cm, respectively, which were lower than that of the powder in Example 1. Furthermore, Example 8, in which 1.5 moles of sulfur atoms were used per 1.0 mole of lithium sulfide, exhibited an ionic conductivity of 3.8 mS / cm. This confirmed that, similar to the example in which 2.0 moles were used, a higher ionic conductivity was obtained compared to that of the powder in the Comparative Example. As described above, the powder of Example 8 exhibited a peak attributable to the argyrodite-type crystal structure, as in Example 1. It is believed that the powder of Example 8 has high ionic conductivity due to the use of elemental sulfur in an amount of sulfur atoms exceeding 1.0 mol per 1.0 mol of lithium sulfide.

[0167] From the above results, it was confirmed that by using an excess amount of elemental sulfur and generating sulfur radicals via lithium polysulfides, soluble polysulfides (i.e., electrolyte precursors) are generated by the reaction of all raw materials together, resulting in the production of a sulfide solid electrolyte with improved ionic conductivity. On the other hand, in Comparative Examples 1 and 2, although the peak due to lithium sulfide disappeared, the reaction of all raw materials did not proceed well, and therefore the sulfide solid electrolyte structure was not sufficiently formed, and high ionic conductivity was not obtained.

[0168] As shown in Figures 10, 11, and 12, there was no significant difference in the powders obtained by heating at 130°C, 250°C, and 430°C in Examples 2 and 7. This indicates that changing the amount of solvent used does not significantly affect the resulting powder as long as the amount of ethanol is maintained. The ionic conductivity of the powders in Examples 2 and 7 was also comparable, at 5.3 mS / cm and 4.5 mS / cm, respectively. These results demonstrate that maintaining the amount of alcohol solvent is particularly effective among alcohol solvents, ether solvents, and nitrile solvents, which are solvents containing heteroatoms such as oxygen and nitrogen atoms.

[0169] According to Examples 9 and 11, it was confirmed that a crystalline sulfide solid electrolyte having an argyrodite-type crystal structure can be obtained without using an alcohol solvent, an ether solvent, and a nitrile solvent in combination as the solvent for mixing the raw material ingredients, as in Examples 1 to 8. Furthermore, according to Examples 9 to 11, it was also found that when an alcohol solvent is used as the solvent, the amount of the alcohol solvent used can be widely adopted, and when an ether solvent and a nitrile solvent are used, the ratio of these solvents used is not limited to a single ratio and can be widely adopted.

[0170] Example 12 In a glove box under a nitrogen atmosphere, 0.2590 g of lithium sulfide, 0.4177 g of diphosphorus pentasulfide, and 0.3616 g of elemental sulfur were mixed using a mortar and introduced into a 100 mL reaction vessel (Reaction Vessel 1) together with a stirrer. Similarly, 0.1776 g of lithium iodide was weighed out and introduced into another 100 mL reaction vessel (Reaction Vessel 2) together with a stirrer. Under a nitrogen atmosphere, 32.62 mL of a mixed solvent of ethanol (EtOH), tetrahydrofuran (THF), and acetonitrile (ACN) (the total amount of tetrahydrofuran (THF) and acetonitrile (ACN) was 512.7 parts by volume relative to 1.0 part by volume of ethanol (EtOH); the volume ratio of ethanol:tetrahydrofuran:acetonitrile was 0.0039:1:1) was added to Reaction Vessel 1, and the mixture was stirred for 10 minutes using a magnetic stirrer. Next, the solution from reaction vessel 1 was added to reaction vessel 2, and further mixing was carried out by stirring with a magnetic stirrer for 10 minutes. Next, using a vacuum pump and an oil bath, heating was carried out at room temperature (20°C) under reduced pressure for 1 hour (first heating-1) and at 130°C under reduced pressure for 1 hour (first heating-2). Furthermore, the powder obtained in the first heating was heated at 170°C under reduced pressure for 2 hours (second heating-1), and a powder was obtained.

[0171] Powder XRD diffraction measurements were performed on the powders obtained by the first heating at 130° C. and the second heating at 170° C. The X-ray diffraction spectra of the powder obtained by heating at 130° C. are shown in Figures 13 and 21, and the X-ray diffraction spectra of the powder obtained by heating at 170° C. are shown in Figures 14 and 22.

[0172] Example 13 In a glove box under a nitrogen atmosphere, 0.6294 g of lithium sulfide, 1.0149 g of diphosphorus pentasulfide, 0.6589 g of elemental sulfur, 0.1400 g of lithium bromide, and 0.2157 g of lithium iodide were mixed using a mortar and introduced into a 100-milliliter reaction vessel together with a stirrer, and 79.29 mL of a mixed solvent of ethanol (EtOH) and tetrahydrofuran (THF) (the amount of tetrahydrofuran (THF) and acetonitrile (ACN) used relative to 1.0 part by volume of ethanol (EtOH) was 510.5 parts by volume (acetonitrile (ACN) was not used); ethanol:tetrahydrofuran:acetonitrile=0.00196:1:0 (volume ratio)) was added, and the mixture was stirred and mixed for 10 minutes using a magnetic stirrer. Next, using a vacuum pump and an oil bath, heating was performed at room temperature (20°C) under reduced pressure for 1 hour (first heating-1) and at 130°C under reduced pressure for 1 hour (first heating-2). Furthermore, the powder obtained by the first heating was heated at 200°C under reduced pressure for 2 hours (second heating-1) to obtain a powder.

[0173] Powder XRD diffraction measurements were performed on the powders obtained by the first heating at 130°C and the second heating at 200°C. Figure 21 shows the X-ray diffraction spectrum of the powder obtained by heating at 130°C, and Figure 22 shows the X-ray diffraction spectrum of the powder obtained by heating at 200°C (the X-ray diffraction spectra in these figures also show those of Example 12 and Comparative Example 3). In addition, the ionic conductivity of the powder obtained by heating at 200°C in Example 13 was measured. The results are shown in Table 2.

[0174] Example 14 Powders were obtained in the same manner as in Example 13, except that the amount of solvent used was the amount shown in Table 2. Powder XRD diffraction measurements were performed on the powders obtained by the first heating at 130°C and the second heating at 200°C. The X-ray diffraction spectrum of the powder obtained by heating at 130°C is shown in Figure 21, and the X-ray diffraction spectrum of the powder obtained by heating at 200°C is shown in Figure 22 (the X-ray diffraction spectra in these figures also include those of Example 12 and Comparative Example 3). In addition, the ionic conductivity of the powder obtained by heating at 200°C in Example 14 was measured. The results are shown in Table 2.

[0175] (Comparative Example 3) A powder of Comparative Example 3 was obtained in the same manner as in Example 12, except that the amount of elemental sulfur used was changed from 0.3616 g to 0.1808 g in Example 12. X-ray diffraction spectra of the powder obtained by heating at 130°C in Comparative Example 3 are shown in Figures 13 and 21, and X-ray diffraction spectra of the powder obtained by heating at 170°C are shown in Figures 14 and 22. The raw materials and solvents used in Example 12 and Comparative Example 3, as well as the amount of elemental sulfur used, are summarized in Table 2 below.

[0176] *1. Raw material supply methods D and E are as follows. D: Lithium sulfide, diphosphorus pentasulfide, and elemental sulfur were mixed, and then lithium iodide was mixed. E: Lithium sulfide, diphosphorus pentasulfide, elemental sulfur, lithium iodide, and lithium bromide were mixed simultaneously.

[0177] 13 and 14 (and FIGS. 21 and 22), the powder obtained in Example 12 had peaks at 2θ = 20.3° and 23.9° attributable to the thiolisiconregion II crystal structure, confirming that it was a sulfide solid electrolyte having a thiolisiconregion II crystal structure. Sulfide solid electrolytes having a thiolisiconregion II crystal structure are known to have high ionic conductivity, similar to the sulfide solid electrolyte having the argyrodite crystal structure, and the powder obtained in Example 12 is considered to be a sulfide solid electrolyte with high ionic conductivity.

[0178] As shown in Figures 13 and 14 (and Figures 21 and 22), the powder obtained in Comparative Example 3 does not show peaks at 2θ = 20.3° and 23.9° that are attributable to the thiolicon region II crystal structure, but shows peaks at 2θ = 20.8° and 27.9° that are attributable to Li ７ P ２ S ８ I or Li ４ P.S. ４ A peak thought to be due to I was observed. In addition, a peak due to lithium sulfide was confirmed at 2θ = 27.0°, which indicated that the reaction did not proceed efficiently.

[0179] Examples 13 and 14 are examples in which an alcohol solvent and an ether solvent were used as solvents. As shown in Figures 21 and 22, the powders obtained in these examples had peaks at 2θ = 20.3° and 23.9° attributable to the thiolicon region II crystal structure, similar to the powder obtained in Example 12, and it was confirmed that they were sulfide solid electrolytes having the thiolicon region II crystal structure and had high ionic conductivity.

[0180] According to the method for producing a sulfide solid electrolyte of this embodiment, it is possible to efficiently provide a sulfide solid electrolyte with improved ionic conductivity. The sulfide solid electrolyte obtained by the production method of this embodiment is suitable for use in batteries, particularly batteries used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. Mixing a raw material-containing material in a solvent, which contains multiple raw materials, each containing at least one atom selected from lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. Next, heat it. Includes, The aforementioned raw material contains elemental sulfur and lithium sulfide, The amount of elemental sulfur used is greater than 1.0 mole per 1.0 mole of lithium sulfide. A method for producing a sulfide solid electrolyte.

2. The method for producing a sulfide solid electrolyte according to claim 1, wherein the halogen atom is at least one atom selected from chlorine atoms, bromine atoms, and iodine atoms.

3. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the solvent is an organic solvent containing at least one atom selected from oxygen atoms and nitrogen atoms.

4. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the solvent is at least one organic solvent selected from alcohol solvents, ether solvents, and nitrile solvents.

5. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the solvent comprises an alcohol solvent.

6. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the solvent comprises an alcohol solvent and at least one organic solvent selected from an ether solvent and a nitrile solvent.

7. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the solvent is an organic solvent containing an alcohol solvent, an ether solvent, and a nitrile solvent.

8. The method for producing a sulfide solid electrolyte according to claim 5, wherein the amount of alcohol solvent used is 0.005 moles or more and 20.0 moles or less per 1.0 mole of lithium sulfide.

9. The method for producing a sulfide solid electrolyte according to claim 6, wherein the total amount used of the ether solvent and the nitrile solvent is 2.0 parts by volume or more and 10,000.0 parts by volume or less, relative to 1.0 part by volume of the alcohol solvent used.

10. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the heating temperature in the heating process is 20°C or more and 500°C or less.

11. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the heating is performed by a first heating at a heating temperature of 20°C or more and less than 150°C, and a second heating at a heating temperature of 150°C or more and 500°C or less.

12. A method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein the raw materials are mixed simultaneously during the mixing process.

13. The method for producing a sulfide solid electrolyte according to claim 1 or 2, wherein, in the mixing process, a raw material group 1 including some raw materials selected from the raw materials is mixed, and then a raw material group 2 including raw materials other than the selected raw materials is mixed.

14. The method for producing a sulfide solid electrolyte according to claim 13, wherein the raw material group 1 includes elemental sulfur.

15. The method for producing a sulfide solid electrolyte according to claim 13, wherein the raw material group 1 comprises a raw material containing at least one atom selected from lithium atoms, phosphorus atoms, and sulfur atoms, elemental sulfur, and lithium sulfide, and the raw material group 2 comprises a raw material containing halogen atoms.

16. A method for producing a sulfide solid electrolyte according to claim 1 or 2, comprising producing a crystalline sulfide solid electrolyte having an argyrodite-type crystal structure or a thiolysicon-type II crystal structure.