JP7400492B2 - Method for manufacturing sulfide solid electrolyte - Google Patents

Description

The present invention relates to a method for producing a sulfide-based solid electrolyte.

Conventionally, lithium ion secondary batteries have been widely used in applications such as portable information terminals and portable electronic devices. The electrolyte used in lithium ion secondary batteries usually uses a flammable organic solvent as the electrolyte. For this reason, lithium-ion secondary batteries usually have a strong exterior to prevent organic solvent from leaking, and also have functions to protect against the risk of electrolyte leaking. There are constraints on the structure of

In addition, in recent years, the use of lithium-ion secondary batteries has expanded to include electric vehicles, hybrid electric vehicles, airplanes, and other moving vehicles, as well as stationary power storage systems, and high-capacity lithium-ion secondary batteries are in demand. . High-capacity lithium-ion secondary batteries are required to have even higher levels of safety.

Under these circumstances, lithium ion secondary batteries using solid electrolytes that do not use flammable organic solvents and can achieve high safety are attracting attention.

Sulfide-based solid electrolytes and oxide-based solid electrolytes are known as representative examples of solid electrolytes. Among these, sulfide-based solid electrolytes have higher electrical conductivity than oxide-based solid electrolytes, and are easier to form solid-solid interfaces with reduced interfacial resistance between electrode active materials and solid electrolytes. It is attracting particular attention for the following reasons.

For example, in Patent Document 1, as a sulfide-based solid electrolyte, _M1 element (at least one selected from the group consisting of Li, Na, K, Mg, Ca, and Zn), _M2 element (P, Sb, A sulfide-based solid containing at least one element selected from the group consisting of Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb) and S element and having a predetermined crystal structure. Inventions related to electrolyte materials are described. In Patent Document 1, one of the methods for manufacturing the sulfide-based solid electrolyte material is to produce amorphous ions by mechanical milling using a raw material composition containing an _M1 element, an _M2 element, and an S element. The method may include an ion conductive material synthesis step of synthesizing a conductive material, and a heating step of heating the amorphous ion conductive material (precursor) to obtain a predetermined sulfide-based solid electrolyte material. Are listed.

International Publication No. 2011/118801

The sulfide-based solid electrolyte described in Patent Document 1 has excellent ionic conductivity. However, in the manufacturing method, the amorphous ion conductive material is prepared by mechanical milling. For this reason, a special device for mechanical milling may be required, and a method for manufacturing a sulfide-based solid electrolyte that is more industrially suitable is required.

Further, when the ion conductive material is heated to produce a sulfide-based solid electrolyte, it is sealed in a vacuum to prevent defects due to volatilization of sulfur (S). For this reason, it is difficult to industrially produce sulfide-based solid electrolytes. In addition, in a vacuum state, sulfur tends to escape during the manufacturing process of the sulfide-based solid electrolyte, resulting in a sulfide-based solid electrolyte that still lacks sulfur for the desired chemical composition, and the desired ionic conductivity may not be obtained. was there.

As a result, there has been a problem in that it is difficult to industrially produce a sulfide-based solid electrolyte having high ionic conductivity.

Therefore, the inventors of the present invention conducted extensive studies to solve the above problems. As a result, instead of mechanical milling, a method was adopted in which the precursor was synthesized in a solvent (liquid phase method), and the precursor obtained by the liquid phase method was heat-treated in the presence of elemental sulfur vapor. The inventors have discovered that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention includes the following aspects.

[1] A homogeneous solution or slurry containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. a solutionizing step of preparing a solution;
a drying step of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor;
a heat treatment step of heating the precursor in the presence of sulfur vapor to produce a solid electrolyte;
including;
A method for producing a sulfide-based solid electrolyte, wherein the sulfur vapor is generated by heating elemental sulfur at a temperature higher than its melting point.
[2] The manufacturing method according to [1] above, wherein the sulfide-based solid electrolyte is an LGPS-based solid electrolyte.
[3] The manufacturing method according to [1] or [2] above, wherein the metal element contains a silicon element.
[4] The production method according to any one of [1] to [3] above, wherein the homogeneous solution or slurry solution is prepared from raw materials containing Li ₂ S, P ₂ S ₅ and SiS ₂ .
[5] The solution forming step is a step of preparing a Li-Si-S homogeneous solution from a first raw material containing Li ₂ S and SiS ₂ ;
preparing a Li-P-S slurry solution from a second raw material containing Li ₂ S and P ₂ S ₅ ;
The Li-Si-S homogeneous solution, the Li-P-S slurry solution, and at least one lithium halide selected from the group consisting of lithium chloride, lithium bromide, and lithium iodide are mixed to prepare Li-Si. - preparing a PSX slurry solution (X is the halogen);
The manufacturing method according to any one of [1] to [4] above, comprising:
[6] The manufacturing method according to any one of [1] to [5] above, wherein the heat treatment step is performed under saturated vapor pressure of sulfur.
[7] The manufacturing method according to any one of [1] to [6] above, wherein the heating temperature in the heat treatment step is 250 to 550°C.
[8] The manufacturing method according to any one of [1] to [7] above, wherein the heat treatment step is performed under sulfur reflux.

According to the present invention, a sulfide-based solid electrolyte having high ionic conductivity can be industrially produced.

It is a schematic diagram of the heating container which performs the heat treatment process concerning one embodiment of the present invention. FIG. 2 is a schematic diagram showing the crystal structure of an LGPS-based solid electrolyte. 1 is a graph showing the results of X-ray diffraction measurements of LGPS-based solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1. 1 is a graph showing the results of Raman spectroscopy of LGPS-based solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1.

The present invention will be explained in detail below. Note that the embodiments described below do not limit the present invention, and various modifications can be made within the scope of the spirit of the present invention.

The present invention provides a homogeneous solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. a solution process of preparing a slurry solution; a drying process of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor; and producing a solid electrolyte by heating the precursor in the presence of sulfur vapor. and a heat treatment step, wherein the sulfur vapor is generated by heating elemental sulfur at a temperature equal to or higher than its melting point.

The sulfide-based solid electrolyte produced by the above method contains a lithium element, a phosphorus element, and a sulfur element, and also contains at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. . Examples of such sulfide-based solid electrolytes include glass ceramic, argyrodite, Thio-LISICON, and LGPS. Among these, LGPS-based solid electrolytes are preferred as the sulfide-based solid electrolytes from the viewpoint of ionic conductivity.

In addition, in this specification, "LGPS-based solid electrolyte" is a solid electrolyte having a crystal structure of an LGPS type phase.

Figure 2 shows the crystal structure of the LGPS solid electrolyte. FIG. 2 is a schematic diagram showing the crystal structure of the LGPS solid electrolyte. The LGPS-based solid electrolyte consists of an octahedron O composed of lithium and sulfur elements, a tetrahedron T1 composed of phosphorus, germanium, and sulfur elements, and a tetrahedron T2 composed of phosphorus and sulfur elements. (PS ₄ ^3- anion), the tetrahedron T1 and the octahedron O share an edge, and the tetrahedron T2 and the octahedron O share a vertex. Edge-sharing LiS _{tetratrahedrons} exist one-dimensionally in series within this skeleton, contributing to high ionic conductivity.

The LGPS-based solid electrolyte having the above crystal structure has at least 2θ=17.38±0.50°, 20.18°±0.50°, 20. 44°±0.50°, 23.56±0.50°, 26.96°±0.50°, 29.07±0.50°, 29.58°±0.50° and 31.71± It has a peak at a position of 0.50°.

In addition, the LGPS solid electrolyte having the above crystal structure has a diffraction intensity of the peak at 2θ=29.58°±0.50° as _IA , and a diffraction intensity of the peak at 2θ=27.33°±0.50°. When the strength is I _B , the value of I _B /I _A is preferably less than 0.50, more preferably less than 0.40. Note that by employing the liquid phase method, it is possible to increase the _IA diffraction intensity related to the peak of the LGPS crystal, which has high ionic conductivity, without performing mechanical milling.

The LGPS-based solid electrolyte may be obtained by substituting or inserting various ions into the LGPS-based solid electrolyte described above.

For example, an LGPS-based solid electrolyte in which a halogen element is added and the ion conduction paths are one-dimensionally connected may be made to spread three-dimensionally.

Further, germanium element may be replaced with silicon element and tin element. As a result, the LGPS solid electrolyte has a lithium element as the central element, an octahedron O having six sulfur elements at the vertices of the octahedron, and a tin element as the central element, with four sulfur elements at the vertices of the tetrahedron. A tetrahedron T1 having a silicon element as a central element and four sulfur elements at the vertices of the tetrahedron, and a tetrahedron T2 having a phosphorus element as a central element and four sulfur elements at the vertices of the tetrahedron. A crystal structure in which the tetrahedron T1, the tetrahedron T2, the tetrahedron T3, and the octahedron O share an edge, and the tetrahedron T3 and the octahedron O share a vertex. can be mainly contained.

The LGPS-based solid electrolyte having the above crystal structure has a peak at 2θ=29.58°±0.50° in X-ray diffraction (CuKα: λ=1.5405 Å), and 2θ=27. There is no peak at the position of 33° ± 0.50°, or there is a peak at the position of 2θ = 27.33° ± 0.50°, and the peak is at the position of 2θ = 29.58° ± 0.50°. The value of I _B /I _A is preferably less than 0.50, where I _A is the diffraction intensity of the peak and I _B is the diffraction intensity of the peak at 2θ=27.33°±0.50°.

Furthermore, an oxygen element may be introduced using a compound containing oxygen element, for example, germanium dioxide (GeO ₂ ) as a raw material. As a result, the LGPS-based solid electrolyte has an octahedron O composed of lithium element and sulfur element, a tetrahedron T1 composed of germanium element and sulfur element, and a tetrahedron composed of phosphorus element and sulfur element. The body T2, the tetrahedron T1, and the octahedron O share an edge, and the tetrahedron T2 and the octahedron O mainly contain a crystal structure in which the vertices are shared. At this time, part of the sulfur element in at least one of the octahedron O, the tetrahedron T1, and the tetrahedron T2 is replaced with an oxygen element. By introducing the O element, the size of the tunnel in the crystal through which Li ions pass changes to a size that facilitates conduction, and the ionic conductivity can be increased.

The LGPS-based solid electrolyte having the above crystal structure has a peak at 2θ=29.58°±0.50° in X-ray diffraction (CuKα: λ=1.5405 Å), and 2θ=27. There is no peak at the position of 33° ± 0.50°, or there is a peak at the position of 2θ = 27.33° ± 0.50°, and the peak is at the position of 2θ = 29.58° ± 0.50°. The value of I _B /I _A is preferably less than 0.50, where I _A is the diffraction intensity of the peak and I _B is the diffraction intensity of the peak at 2θ=27.33°±0.50°.

In addition, the LGPS solid electrolyte having the above crystal structure has a diffraction intensity of the peak at 2θ=29.58°±0.50° as _IA , and a diffraction intensity of the peak at 2θ=27.33°±0.50°. When the strength is I _B , the value of I _B /I _A is preferably less than 0.50, more preferably less than 0.40.

Among the above-mentioned LGPS-based solid electrolytes, the metal element preferably contains silicon element and tin element, and more preferably contains silicon element. Thereby, the LGPS-based solid electrolyte can be manufactured at low cost.

In one embodiment, among the above-mentioned LGPS-based solid electrolytes, it is preferable to contain silicon element from the viewpoint of economical efficiency and ionic conductivity, and it is more preferable to contain silicon element and chlorine element from the viewpoint of ionic conductivity. .

The specific composition of the LGPS solid electrolyte is Li ₁₀ GeP ₂ S ₁₂ , Li ₁₀ SnP ₂ S ₁₂ , Li _10.35 Ge _1.35 P _1.65 S ₁₂ , Li _10.35 Si _1.35 P _1.65 S ₁₂ , Li _9.81 Sn _0.81 P _2.19 S ₁₂ , Li ₁₀ (Si _0.5 Ge _0.5 )P ₂ S ₁₂ , Li ₁₀ (Ge _0.5 Sn _0.5 )P ₂ S ₁₂ , Li ₁₀ (Si _0.5 Sn _0.5 )P ₂ S ₁₂ , Li _9.54 Si _1.74 P _1.44 S _11.7 Cl _0.3 , Li ₁₀ GeP ₂ S _11.7 O _0.3 , Li _9.42 Si _1.02 P _2.1 S _9.96 O _2.04 , Li _10.35 [Sn _0.27 Si _1.08 ] P _1.65 S ₁₂ (Li _3.45 [Sn _0.09 Si _0.36 ] P _{0.55 S4} ) etc. can be mentioned.

Solid-phase methods and liquid-phase methods are known as methods for synthesizing the precursor, but liquid-phase synthesis is preferred because it is easy to synthesize on a large scale industrially.

The precursor of the LGPS-based solid electrolyte by the liquid phase method can be produced, for example, according to the method described in International Publication No. 2019/044517. Specifically, the liquid phase method includes a solution process in which raw materials for the LGPS solid electrolyte are dissolved in an organic solvent to prepare a homogeneous solution or slurry solution, and a drying process in which the liquid obtained in the solution process is dried. include. A feature of the liquid phase method is that by reacting and dissolving part or all of the raw materials in an organic solvent, the composition is made uniform and the raw materials are made amorphous.

Hereinafter, a method for producing an LGPS-based solid electrolyte will be described, but the embodiments of the present invention are not limited thereto.

<Solution process>
The solutionizing step includes a homogeneous solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and also containing at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. Alternatively, it is a step of preparing a slurry solution. At this time, the homogeneous solution or slurry solution may further contain other elements. In addition, in this specification, a "homogeneous solution" means a solution in which there is no undissolved solid matter. Moreover, "slurry solution" means a solution containing undissolved solids in the solution.

Examples of the other elements include, but are not particularly limited to, halogen elements (fluorine element, chlorine element, bromine element, iodine element), oxygen element, and the like. These other elements may be contained alone or in combination of two or more.

(Homogeneous solution and slurry solution)
The organic solvent is not particularly limited as long as it does not react with the raw materials or intermediate products. Examples include ether solvents, ester solvents, hydrocarbon solvents, nitrile solvents, and the like. Specific examples include tetrahydrofuran, cyclopentyl methyl ether, diisopropyl ether, diethyl ether, dimethyl ether, dioxane, methyl acetate, ethyl acetate, butyl acetate, and acetonitrile. Particularly preferred is acetonitrile. In order to prevent the raw material composition from deteriorating, it is preferable to remove oxygen and water from the organic solvent. In particular, the water content is preferably 100 ppm or less, more preferably 50 ppm or less. The above organic solvents may be used alone or in combination of two or more.

Other elements include, but are not particularly limited to, halogen elements selected from the group consisting of chlorine elements, bromine elements, and iodine elements, oxygen elements, and the like. Among these, from the viewpoint of ionic conductivity, halogen elements are preferred, and chlorine elements are more preferred. In order to expand the solid solution region, oxygen element may be included. Note that the other elements may be contained alone or in combination of two or more types.

The homogeneous solution and slurry solution are prepared by combining raw materials that serve as sources of each element. The raw materials are not particularly limited, but include a lithium source, a phosphorus source, a sulfur source, a silicon source, a germanium source, a tin source, and a chlorine source. Examples include raw materials, raw materials that serve as a bromine source, raw materials that serve as an iodine source, raw materials that serve as an oxygen source, and the like.

The raw material serving as the lithium source includes, but is not particularly limited to, lithium sulfide (Li ₂ S), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and the like.

Raw materials that serve as phosphorus sources include elemental phosphorus (P), diphosphorus trisulfide (P ₂ S ₃ ), diphosphorus pentasulfide (P ₂ S ₅ ), phosphorus pentachloride (PCl ₅ ), and phosphorus tribromide (PBr ₃ ), phosphorus pentabromide ( _PBr5 ), and the like.

Raw materials that serve as sulfur sources include elemental sulfur, lithium sulfide (Li ₂ S), phosphorus sulfide (P ₂ S ₅ ), silicon sulfide (SiS ₂ ), germanium sulfide (GeS ₂ ), tin sulfide (SnS), and trisulfide. Examples include diphosphorus (P ₂ S ₃ ), diphosphorus pentasulfide (P ₂ S ₅ ), aluminum sulfide (Al ₂ S ₃ ), diboron trisulfide (B ₂ S ₃ ), and the like.

Examples of raw materials serving as a silicon source include silicon sulfide (SiS ₂ ), silicon (Si), silicon dioxide (SiO ₂ ), and the like.

Examples of raw materials serving as germanium sources include germanium sulfide (GeS ₂ ), germanium (Ge), germanium dioxide (GeO ₂ ), and the like.

Examples of raw materials for tin sources include tin sulfide (SnS), tin (II) oxide (SnO), tin (IV) oxide (SnO ₂ ), tin (VI) oxide (SnO ₃ ), and tin (Sn). It will be done.

Examples of raw materials serving as a chlorine source include lithium chloride (LiCl), phosphorus pentachloride (PCl ₅ ), and the like.

Examples of raw materials serving as a bromine source include lithium bromide (LiBr), phosphorus tribromide (PBr ₃ ), phosphorus pentabromide (PBr ₅ ), and the like.

Examples of the raw material serving as the iodine source include lithium iodide (LiI).

Raw materials that serve as oxygen sources include lithium oxide (LiO ₂ ), phosphorus pentoxide (P ₂ O ₅ ), silicon dioxide (SiO ₂ ), germanium dioxide (GeO ₂ ), tin (II) oxide (SnO), and tin oxide. (IV) (SnO ₂ ), tin (IV) oxide (SnO ₃ ), and the like.

These raw materials may be used alone or in combination of two or more. By changing the composition of these raw materials, a desired sulfide-based solid electrolyte can be manufactured.

As mentioned above, in the solutionizing step, a homogeneous solution or a slurry solution is prepared by appropriately combining the above-mentioned raw materials.

According to one embodiment, the solutionizing step includes preparing a Li-Si-S homogeneous solution from a first raw material containing Li ₂ S and SiS ₂ and a second solution containing Li ₂ S and P ₂ S ₅ . A step of preparing a Li-P-S slurry solution from the raw materials, the Li-Si-S homogeneous solution, the Li-P-S slurry solution, and a group consisting of lithium chloride, lithium bromide, and lithium iodide. The method preferably includes the step of preparing a Li-Si-PSX slurry solution (X is the halogen) by mixing at least one lithium halide selected from the following.

In producing the LGPS-based solid electrolyte precursor, _the molar ratio of Li ₂ S and SiS ₂ as raw materials is not particularly limited, but for example, Li ₂ The amount of S used is preferably in the range of 1.5 to 5 mol. Furthermore, the molar ratio of the raw materials P ₂ S ₅ and SiS ₂ is not particularly limited, but for example, the amount of P ₂ S ₅ used is 0.3 to 1 mol of SiS ₂ . It is preferably within the range of 1 mol. This composition is preferable because LGPS crystals are easily formed.

Hereinafter, each step of the solutionization step will be described in detail using as an example the case of manufacturing the LGPS-based solid electrolyte containing Si and halogen according to the above-described embodiment, but the present invention is not limited thereto.

(Step of preparing Li-Si-S homogeneous solution)
A Li-Si-S homogeneous solution is prepared from a first raw material containing Li ₂ S and SiS ₂ .

Although the method for preparing the Li-Si-S homogeneous solution is not particularly limited, it is usually prepared by mixing the first raw materials in an organic solvent and removing solids contained in the resulting solution.

When the first raw materials are mixed, Li ₂ S, SiS _2, etc. usually react to obtain a solution in which lithium element, silicon element, and sulfur element are dissolved.

The mixing of the first raw materials is preferably carried out under an inert gas atmosphere, and more preferably carried out under an atmosphere of nitrogen gas, helium gas, or argon gas. By mixing the first raw materials in an inert gas atmosphere, occurrence of deterioration, decomposition, etc. of SiS ₂ can be prevented or suppressed.

The mixing temperature of the first raw material is not particularly limited. Although the reaction proceeds slowly even at room temperature (25° C.), heating can be applied to increase the reaction rate. When heating, it is sufficient to carry out the heating at a temperature below the boiling point of the organic solvent, and although it varies depending on the organic solvent used, the temperature is usually below 120°C. It is also possible to carry out under pressure using an autoclave or the like. It is preferable to set the mixing temperature to less than 120° C. because the progress of side reactions can be prevented or suppressed.

The mixing time for the first raw material is preferably 0.1 to 240 hours, more preferably 1 to 200 hours, although it varies depending on the type of organic solvent and the particle size and concentration of the raw material.

If the solution obtained by mixing the first raw materials contains solids, a Li-Si-S homogeneous solution can be obtained by removing the solids.

Methods for removing solids include, but are not particularly limited to, filtration, centrifugation, and the like.

When filtration is performed using a filter, the pore size of the filter is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less.

The content (moles) of each element contained in the resulting Li--Si--S homogeneous solution is determined by a value measured by inductively coupled plasma (ICP) analysis. The total concentration of lithium element (Li), silicon element (Si), and sulfur element (S) in the Li-Si-S homogeneous solution is 0.5 to 20% by mass with respect to the mass of the Li-Si-S homogeneous solution. %, more preferably 1 to 15% by weight, even more preferably 2 to 10% by weight. It is preferable that the total concentration is 0.5% by mass or more because the reaction efficiency can be increased and the amount of organic solvent used can be reduced. On the other hand, it is preferable that the total concentration is 20% by mass or less, since precipitation of solids can be prevented or suppressed and the form of a homogeneous solution can be maintained.

In addition, from the usage ratio (molar ratio) of Li ₂ S and SiS ₂ and the total concentration of the lithium element (Li), silicon element (Si), and sulfur element (S), the Li-Si-S homogeneous solution and removal It is possible to understand the composition of the solid matter.

The obtained homogeneous solution preferably has a molar ratio of Li/Si=0.6 to 2.0, more preferably Li/Si=0.7 to 1.6, and Li/Si=0. More preferably, it is 8 to 1.4. Note that the content (mol) of each element in the homogeneous solution is measured by ICP.

(Step of preparing Li-P-S slurry solution)
A Li-P-S slurry solution is prepared from a second raw material containing Li ₂ S and P ₂ S ₅ .

The second raw material may further contain other raw materials. Other raw materials that may be included in the second raw material are the above-mentioned raw materials other than Li ₂ S and P ₂ S ₅ .

Although the method for preparing the Li-P-S slurry solution is not particularly limited, it is usually prepared by mixing P ₂ S ₅ and Li ₂ S in an organic solvent.

The usage ratio (molar ratio) of Li ₂ S and P ₂ S ₅ in the second raw material is preferably Li ₂ S/P ₂ S ₅ =1.0 to 25, and preferably 2.0 to 20. It is more preferably 2.5 to 15.

At this time, Li ₂ S may be added in its entirety at once, or may be added in two or more parts.

The mixing of the second raw materials is preferably performed under an inert gas atmosphere, and more preferably under an atmosphere of nitrogen gas, helium gas, or argon gas. By mixing the second raw material in an inert gas atmosphere, deterioration, decomposition, etc. of the second raw material can be prevented or suppressed.

Regarding the mixing temperature of the second raw materials, the reaction proceeds even at room temperature, but it can also be heated to increase the reaction rate. When heating, it is sufficient to carry out the heating at a temperature below the boiling point of the organic solvent, and although it varies depending on the organic solvent used, the temperature is usually below 120°C. It is also possible to carry out under pressure using an autoclave or the like. It is preferable to set the mixing temperature to less than 120° C. because the progress of side reactions can be prevented or suppressed.

The mixing time of the second raw material is not particularly limited, but is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

(Step of preparing Li-Si-P-SX slurry solution)
The step of preparing a Li-Si-P-S-X (X represents the halogen) slurry solution is prepared by mixing a Li-Si-S homogeneous solution, a Li-P-S slurry solution, and a lithium halide. be done.

The order of mixing the Li--Si--S homogeneous solution, the Li--P--S slurry solution, and the lithium halide is not particularly limited.

The lithium halide is at least one selected from the group consisting of lithium chloride, lithium bromide, and lithium iodide. Among these, it is preferable to use lithium chloride.

Regarding the amount of lithium halide used, LiCl/P ₂ S ₅ is preferably 0.01 to 2, and 0.01 to 2, per 1 mol of P ₂ S ₅ contained in the Li--P--S slurry solution to be mixed. It is more preferably 05 to 1.5, and even more preferably 0.1 to 1.

In the solutionization step, elemental sulfur may be added as appropriate. The method of adding elemental sulfur is not particularly limited, but includes a method of adding it when preparing a Li-Si-S homogeneous solution, a method of adding it when preparing a Li-P-S slurry solution, a method of adding it when preparing a Li-Si-P Examples include a method of adding it when preparing a -SX slurry solution. For example, when elemental sulfur is added when preparing a Li-Si-S homogeneous solution, elemental sulfur is preferably added together with Li ₂ S and SiS ₂ .

The amount of elemental sulfur to be added cannot be determined unconditionally because it is affected by the size and shape of the firing furnace used in the heat treatment process, the flow rate of atmospheric gas, the particle size of the precursor, etc., but it is , preferably 1 to 100% by mass, more preferably 2 to 10% by mass. If the amount of elemental sulfur added is 1.0 to 100% by mass based on the solid electrolyte raw material, it is possible to produce an LGPS-based solid electrolyte with few impurities and stable performance.

As described above, as an embodiment of the solutionization process, a Li-Si-P-S-X slurry solution is prepared by mixing a Li-Si-S uniform solution, a Li-P-S slurry solution, and a lithium halide powder. The form was explained. However, the solution process is not limited to this embodiment, and may include a form in which Li-Si-S homogeneous solution, Li-P-S homogeneous solution, Li ₂ S, and lithium halide are mixed, or a Li-P-S homogeneous solution. , Li ₂ S, SiS ₂ and lithium halide may be mixed together.

In addition, when preparing a Li-P-S homogeneous solution in the solutionization process, Li ₂ S and P ₂ S ₅ are mixed at a molar ratio of Li ₂ S/P ₂ S ₅ =0.7 to 1.5. It is preferable to generate by mixing and reacting in an organic solvent, more preferably Li ₂ S / P ₂ S ₅ = 0.75 to 1.4, particularly preferably Li ₂ S / P ₂ S ₅ =0.8 to 1.35. When the molar ratio of Li ₂ S/P ₂ S ₅ is in the range of 0.7 to 1.5, Li ₂ S and P ₂ S ₅ can be made into a solution at room temperature. A Li ₂ S/P ₂ S ₅ molar ratio within the above range is preferred because Li ₂ S and P ₂ S ₅ can be suitably dissolved at room temperature. The solution obtained by mixing Li ₂ S and P ₂ S ₅ may contain unreacted Li ₂ S and P ₂ S ₅ , or may contain impurities mixed in from Li ₂ S and P ₂ S ₅ . May be included. Impurities hardly dissolve in the solvent and become insoluble solids. Therefore, by filtering or centrifuging the obtained solution to remove undissolved solids and separate the solution, a highly pure homogeneous solution of Li-P-S can be obtained.

<Drying process>
The drying step is a step of removing the organic solvent from the homogeneous solution or slurry solution obtained in the above-mentioned solution forming step to obtain a precursor. Hereinafter, in one embodiment of the solution forming step, the drying step is a step of removing the organic solvent from the Li-Si-PSX slurry solution to obtain a precursor.

The drying step is preferably carried out in an inert gas atmosphere or a vacuum atmosphere, and more preferably carried out in an atmosphere of nitrogen gas, helium gas, or argon gas.

The drying temperature is preferably 60 to 250°C, more preferably 100 to 250°C. It is preferable that the drying temperature is 60° C. or higher because it is possible to suppress or prevent the influence of carbonization of the organic solvent remaining in the precursor in the heat treatment step described below. On the other hand, it is preferable that the drying temperature is 250° C. or lower because deterioration of the precursor can be suppressed or prevented.

The drying time is preferably 0.5 to 24 hours, more preferably 1 to 8 hours.

<Heat treatment process>
The heat treatment step is a step in which the precursor obtained in the drying step is heated in the presence of sulfur vapor to produce a solid electrolyte. At this time, the sulfur vapor is generated by heating elemental sulfur at a temperature higher than its melting point.

By heating the precursor, it can be crystallized and a sulfide-based solid electrolyte can be obtained. However, sulfur sometimes volatilized from the precursor during the heat treatment process. In addition, moisture and oxygen that may be contained inside the precursor or in the gas atmosphere may react with sulfur in the precursor, decomposing the sulfur and converting it into sulfur dioxide or hydrogen sulfide. As a result, the resulting sulfide-based solid electrolyte may lack elemental sulfur relative to the desired chemical composition. As a result, the resulting sulfide-based solid electrolyte may have a problem in that, for example, a constant ionic conductivity is not obtained, or rather the ionic conductivity is decreased.

In contrast, in this embodiment, the heat treatment step is performed in the presence of sulfur vapor. As a result, volatilization of sulfur from the precursor is suppressed. Further, moisture and oxygen that may be contained inside the precursor or in the gas atmosphere easily react with sulfur vapor, so that volatilization of sulfur in the precursor is suppressed. As a result, a sulfide-based solid electrolyte having a desired chemical composition can be produced, and the sulfide-based solid electrolyte has constant and high ionic conductivity.

The heat treatment is preferably performed in an inert gas atmosphere, and examples of the inert gas include nitrogen, helium, and argon, with argon being particularly preferred. The concentrations of oxygen and moisture in the inert gas are preferably low, both preferably at most 1000 ppm, more preferably at most 100 ppm, particularly preferably at most 10 ppm.

The temperature of the heat treatment varies depending on the composition of the desired sulfide solid electrolyte, etc., but is preferably 250 to 700°C, more preferably 300 to 650°C, and 300 to 550°C. The temperature is more preferably 350 to 550°C, particularly preferably 400 to 550°C. It is preferable that the temperature of the heat treatment is 250° C. or higher, since the temperature exceeds the melting point of elemental sulfur (115° C.), and sulfur vapor is suitably generated, and the precursor is suitably crystallized. On the other hand, it is preferable that the temperature of the heat treatment is 700° C. or lower because deterioration of the sulfide-based solid electrolyte can be prevented or suppressed.

Although the heat treatment time varies slightly depending on the heating temperature, sufficient crystallization can usually be achieved within the range of 0.1 to 24 hours.

In one embodiment, the heat treatment is preferably performed under saturated vapor pressure of sulfur. By performing the heat treatment under the saturated vapor pressure of sulfur, sufficient sulfur vapor is provided within the heat treatment system. As a result, volatilization of sulfur from the precursor can be suppressed.

The method of introducing sulfur vapor is not particularly limited, and sulfur vapor may be prepared by separately heating elemental sulfur and introduced into the precursor heat treatment system, or the sulfur vapor may be introduced into the precursor heat treatment system. Elemental sulfur may be heated to generate sulfur vapor.

When generating sulfur vapor from elemental sulfur in the heat treatment system of the precursor, elemental sulfur may be placed at the same location as the precursor or at a different location from the precursor. It is preferable to arrange it at a location different from the precursor. Further, the heat source for heating elemental sulfur may be the same as or different from the heat source for heating the precursor, but from the viewpoint of thermal efficiency, it is preferable that the heat source be the same.

In one embodiment, sulfur vapor is preferably generated within the system for heat treatment of the precursor by placing the elemental sulfur in a separate location from the precursor and heating the precursor and elemental sulfur with the same heat source. . FIG. 1 is a schematic diagram of a heating container that performs the heat treatment process according to the embodiment. The heating container 1 in FIG. 1 has a glass inner cylinder 2 and a glass outer cylinder 3. A precursor 4 is placed in the glass inner cylinder 2, and elemental sulfur 5 is placed in the glass outer cylinder 3. Note that the heating container 1 is sealed with a stopper (not shown), and argon gas is introduced and discharged through a branch pipe. Furthermore, a thermocouple 6 is provided to measure the temperature inside the glass inner cylinder 2.

Here, when the entire glass inner tube 2 of the heating container 1 is heated using the tubular furnace 7, the precursor 4 is heated. At this time, since the elemental sulfur 4 of the glass outer cylinder 3 is also heated at the same time, sulfur vapor is generated, and the heat treatment is performed in the presence of sulfur vapor. Note that since the upper part of the glass outer cylinder 3, which is not covered by the tube furnace 7, is not directly heated and has a lower temperature than the bottom of the heating container 1, some of the sulfur vapor liquefies or solidifies, and the glass inner cylinder 3 is heated. 2 and/or the glass outer cylinder 3. When the amount of elemental sulfur 4 used is above a certain level, the heat treatment can be performed in a reflux state of sulfur vapor. In addition, after the sulfide-based solid electrolyte has been crystallized by heat treatment, further heat treatment causes sulfide-based It is also possible to suppress contamination of the solid electrolyte with elemental sulfur.

In this way, when generating sulfur vapor from elemental sulfur in the precursor heat treatment system, sulfur contamination to the sulfide-based solid electrolyte can be prevented by locating elemental sulfur in a location different from the precursor. can be suppressed.

Further, the heat treatment is preferably performed under sulfur reflux of elemental sulfur. By performing the heat treatment under sulfur reflux of elemental sulfur, volatilization of sulfur in the precursor can be suppressed and a sulfide-based solid electrolyte having a desired chemical composition can be produced. As a result, the sulfide-based solid electrolyte has constant and high ionic conductivity.

Although the amount of elemental sulfur used varies depending on the heat treatment conditions and heating container, it is preferably 10 to 500% by mass, more preferably 50 to 450% by mass, and 100 to 400% by mass, based on the total mass of the precursor. %, particularly preferably 150 to 350% by weight, and most preferably 150 to 250% by weight. It is preferable that the amount of elemental sulfur used is 10% by mass or more because a sufficient amount of sulfur vapor can be generated. On the other hand, when the amount of elemental sulfur used is 500% by mass or less, sulfur contamination to the sulfide-based solid electrolyte can be prevented, which is also economically preferable.

As mentioned above, by adopting a liquid phase method instead of mechanical milling and heat-treating the precursor obtained by the liquid phase method in the presence of elemental sulfur vapor, sulfides with high ionic conductivity can be produced. solid electrolytes can be produced industrially.

<Method for manufacturing all-solid-state batteries>
According to one aspect of the present invention, a method for manufacturing an all-solid-state battery is provided. Note that the term "all-solid battery" refers to a battery that uses a solid electrolyte as an electrolyte. All-solid-state batteries typically include a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

More specifically, the method for manufacturing an all-solid-state battery relates to a method for manufacturing an all-solid-state battery having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. At this time, at least one of the positive electrode layer, solid electrolyte layer, and negative electrode layer is formed using the sulfide-based solid electrolyte produced by the above method.

The solid electrolyte layer is preferably formed using a sulfide-based solid electrolyte produced by the method described above. At this time, the solid electrolyte layer may be composed of the sulfide-based solid electrolyte alone, or may contain other solid electrolytes in combination. Examples of the other solid electrolytes include oxide solid electrolytes, complex hydride solid electrolytes, and the like.

Further, the positive electrode layer and/or the negative electrode layer may be formed using the sulfide-based solid electrolyte produced by the above method. When the sulfide-based solid electrolyte is contained in the positive electrode layer and the negative electrode layer, the positive electrode layer and the negative electrode layer are formed by combining known positive electrode active materials or negative electrode active materials for lithium ion secondary batteries. At this time, the quantitative ratio of the sulfide-based solid electrolyte contained in the positive electrode layer or the negative electrode layer is not particularly limited. Note that the positive electrode layer and the negative electrode layer may contain a known current collector, conductive aid, binder, and the like.

The all-solid-state battery is produced by molding and laminating the above-described positive electrode layer, solid electrolyte layer, and negative electrode layer, but there are no particular restrictions on the method of molding and laminating each layer.

For example, a method in which a solid electrolyte and/or electrode active material is dispersed in a solvent to form a slurry is applied using a doctor blade or spin coating, and then rolled to form a film; vacuum evaporation method, ion plating There are vapor phase methods in which films are formed and laminated using methods such as methane, sputtering, and laser ablation; there are pressure molding methods in which powder is molded using hot press or cold press without applying any temperature, and then layered. .

Since the sulfide-based solid electrolyte produced by the above method is relatively soft, it is particularly preferable to form and laminate each layer by a pressure molding method to produce an all-solid-state battery. Pressure molding methods include hot press, which is performed with heating, and cold press, which is performed without heating, but cold pressing can also be used to form the product satisfactorily.

According to one embodiment of the present invention, there is also provided a molded article obtained by heat-molding the sulfide-based solid electrolyte produced by the above method. The molded body can be suitably used as an all-solid-state battery.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Manufacturing example]
An LGPS-based solid electrolyte precursor containing lithium, phosphorus, sulfur, silicon, and chlorine was produced by a liquid phase method.

(Step of preparing Li-Si-S homogeneous solution)
In a glove box under an argon atmosphere, 4.08 g _{of Li 2 S} (manufactured by Sigma _- Aldrich, purity 99.8%) and 16.18 g of SiS ₂ (manufactured by Hanghzou Ocean Chemical, purity 99%) was charged into a glass container. Furthermore, 2.41 g of elemental sulfur (manufactured by Kojundo Kagaku Co., Ltd., purity 99.99%) was added to the glass container. Next, 630 g of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd., super dehydration grade) was added and mixed at room temperature (25° C.) for 172 hours. The mixture gradually dissolved, but impurities in the raw materials remained at this stage. The obtained solution was filtered using a membrane filter (PTFE, pore size 1.0 μm) to prepare a filtrate (Li-Si-S homogeneous solution).

As a result of ICP analysis of the Li-Si-S homogeneous solution, the Li/Si (molar ratio) was 49.7/50.3. Further, the concentration of (Li ₂ S+SiS ₂ ) was 3.17 wt%.

(Step of preparing Li-P-S slurry solution)
In a glove box under an argon atmosphere, 8.52 g of Li ₂ S (manufactured by Sigma-Aldrich, purity 99.8%) and 13.74 g of P ₂ S ₅ (manufactured by Sigma-Aldrich, purity 99%) were added. Added to a glass container. Next, 220 g of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd., super dehydration grade) was added and mixed at room temperature (25° C.) for 3 hours. Thereafter, 6.71 g of Li ₂ S (manufactured by Sigma-Aldrich, purity 99.8%) was added and mixed for 6 hours to prepare a Li-P-S slurry solution.

(Step of preparing Li-Si-P-S-Cl slurry solution)
In a glove box under an argon atmosphere, 511.83 g of Li-Si-S homogeneous solution and 248.97 g of Li-P-S slurry solution were mixed, and then 1.03 g of LiCl (manufactured by Sigma-Aldrich, (purity 99.99%) were mixed. The resulting mixed solution was stirred at room temperature (25°C) for 12 hours to prepare a Li-Si-P-S-Cl slurry solution.

Note that the charging composition of all solid electrolyte raw materials added to the system is Li _10.05 Si _1.48 P _1.55 S _11.7 Cl _0.3 , and the amount of elemental sulfur input is The content was adjusted to 4.38% by mass.

(drying process)
The prepared Li-Si-P-S-Cl slurry solution was dried under vacuum at 180°C for 4 hours while stirring the solution to remove the solvent, and by cooling to room temperature, the charging composition was changed to Li ₁₀ An LGPS-based solid electrolyte precursor of _.05 Si _1.48 P _1.55 S _11.7 Cl _0.3 was prepared. Note that the solvent was removed while stirring the slurry solution.

[Example 1]
A heat treatment step was performed using the heating container 1 shown in FIG. 1 using the precursor obtained in the production example.

More specifically, in a glove box under an argon atmosphere, 0.5 g of precursor 3 was placed in the glass inner tube 2, and 1.0 g of elemental sulfur 5 (200 g relative to the total mass of the precursor) was placed in the glass outer tube 3. % by mass, manufactured by Kojundo Kagaku Co., Ltd., purity 99.99%).

While flowing argon (G3 grade) at 50 mL/min into the heating container 1, the temperature was raised to 475° C. over 2.5 hours, and then firing was performed at 475° C. for 4 hours, thereby producing an LGPS-based solid electrolyte. At this time, the heat treatment was performed using the tubular furnace 7 so that the entire inner cylinder of the heating container 1 was heated.

In addition, since the melting point of elemental sulfur is 115°C and the boiling point is 445°C, it is considered that the added elemental sulfur existed as sulfur vapor in the heating container during the heat treatment. Furthermore, the temperature of the upper part of the glass outer cylinder is around room temperature, and the sulfur vapor is cooled, so that the sulfur is in a reflux state. Although some elemental sulfur was released outside the heating container, elemental sulfur remained inside the glass outer cylinder when the temperature was lowered to room temperature after the heat treatment was completed. Therefore, it is considered that the heat treatment was performed under sulfur reflux.

The obtained LGPS-based solid electrolyte was subjected to X-ray diffraction measurement using the following method. That is, X-ray diffraction was measured at room temperature (25° C.) in an Ar atmosphere using an X-ray diffraction device “X'Pert3Powder” (CuKα:λ=1.5405 Å, manufactured by PANalytical). As a result, peaks were observed at 2θ = 17.25°, 20.01°, 20.22°, 23.39°, 26.76°, 28.81°, 29.41°, 31.44°, It was confirmed that the obtained sulfide-based solid electrolyte was an LGPS crystal. Note that FIG. 3 shows a graph showing the results of X-ray diffraction measurement of the obtained LGPS-based solid electrolyte.

[Example 2]
Heat treatment was performed under the same conditions as in Example 1, except that 1.5 g (300% by mass of the total mass of the precursor) of S was added to the inner cylinder and outer cylinder of the glass reaction tube.

X-ray diffraction measurements were performed in the same manner as in Example 1. As a result, peaks were observed at 2θ = 17.30°, 20.06°, 20.27°, 23.45°, 26.80°, 28.86°, 29.46°, 31.49°, It was confirmed that the obtained sulfide-based solid electrolyte was an LGPS crystal. Note that FIG. 3 shows a graph showing the results of X-ray diffraction measurement of the obtained LGPS-based solid electrolyte.

[Example 3]
Heat treatment was performed under the same conditions as in Example 1, except that 2.0 g (400% by mass of the total mass of the precursor) of S was added to the inner cylinder and outer cylinder of the glass reaction tube.

X-ray diffraction measurements were performed in the same manner as in Example 1. As a result, peaks were observed at 2θ = 17.23°, 19.99°, 20.19°, 23.37°, 26.74°, 28.80°, 29.39°, 31.43°, It was confirmed that the obtained sulfide-based solid electrolyte was an LGPS crystal. Note that FIG. 3 shows a graph showing the results of X-ray diffraction measurement of the obtained LGPS-based solid electrolyte.

[Comparative example 1]
In the heat treatment process, the LGPS sulfide solid electrolyte was prepared in the same manner as in Example 1, except that elemental sulfur was not added between the glass inner cylinder 2 and the glass outer cylinder 3 of the heating container 1. Manufactured.

In addition, when X-ray diffraction measurement was performed in the same manner as in Example 1, 2θ = 17.22°, 19.98°, 20.17°, 23.38°, 26.72°, 28.79°. Peaks were observed at , 29.39°, and 31.41°, and it was confirmed that the obtained sulfide-based solid electrolyte was an LGPS crystal. Note that FIG. 3 shows a graph showing the results of X-ray diffraction measurement of the obtained LGPS-based solid electrolyte.

<Raman spectroscopy measurement>
(1) Sample Preparation A measurement sample was prepared using a sealed container having a quartz glass (Φ60 mm, thickness 1 mm) as an optical window on the upper part. The sample was placed in contact with quartz glass in a glove box under an argon atmosphere, and the container was sealed and taken out of the glove box for Raman spectroscopic measurements.

(2) Measurement conditions Measurement was performed using a laser Raman spectrophotometer NRS-5100 (manufactured by JASCO Corporation) at an excitation wavelength of 532.15 nm and an exposure time of 20 seconds.

FIG. 4 is a graph showing the results of Raman spectroscopy of the LGPS solid electrolytes obtained in Examples 1 to 3 and Comparative Example 1. As shown in the Raman diffraction results in FIG. 4, peaks were obtained at least at 270±10 cm ⁻¹ and 420±10 cm ⁻¹ in Raman spectroscopy, and peaks corresponding to PS ₄ ³⁻ were obtained.

Although a peak of elemental sulfur is detected near 220 cm ^-1 , since no peak was observed in any of Examples 1 to 3 and Comparative Example 1, elemental sulfur was detected in the obtained fired body. It was confirmed that there was almost no residue left.

<Lithium ion conductivity measurement>
The ionic conductivity of the LGPS solid electrolytes produced in Examples 1 to 3 and Comparative Example 1 was evaluated.

Specifically, the LGPS solid electrolyte was subjected to uniaxial molding (480 MPa) to obtain a disk with a thickness of about 1 mm and a diameter of 10 mm. Next, alternating current impedance measurement ("Sl1260 IMPEDANCE/GAIN-PHASEANALYZER" manufactured by Solartron) was performed at room temperature (25° C.) by a four-probe method, and the lithium ion conductivity was calculated.

The results obtained are shown in Table 1 below.

From the results shown in Table 1, it can be seen that the LGPS solid electrolytes produced in Examples 1 to 3 have high ionic conductivity. Further, by employing the liquid phase method, the LGPS solid electrolyte can be manufactured industrially.

1 Heating container 2 Glass inner cylinder 3 Glass outer cylinder 4 Precursor 5 Elemental sulfur 6 Thermocouple 7 Tubular furnace

Claims (8)

Preparing a homogeneous solution or slurry solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. A solution process to
a drying step of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor;
a heat treatment step of heating the precursor in the presence of sulfur vapor to produce a solid electrolyte;
including;
The sulfur vapor is generated by heating elemental sulfur at a temperature above its melting point,
The solution forming step is a step of preparing a Li-Si-S homogeneous solution from a first raw material containing Li ₂ S and SiS ₂ ;
preparing a Li-P-S slurry solution from a second raw material containing Li ₂ S and P ₂ S ₅ ;
The Li-Si-S homogeneous solution, the Li-P-S slurry solution, and at least one lithium halide selected from the group consisting of lithium chloride, lithium bromide, and lithium iodide are mixed to prepare Li-Si. - preparing a PSX slurry solution (X is the halogen);
A method for producing a sulfide-based solid electrolyte , including : Preparing a homogeneous solution or slurry solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. A solution process to
a drying step of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor;
a heat treatment step of heating the precursor in the presence of sulfur vapor to produce a solid electrolyte;
including;
The sulfur vapor is generated by heating elemental sulfur at a temperature above its melting point,
A method for producing a sulfide-based solid electrolyte , wherein the heat treatment step is performed under saturated vapor pressure of sulfur. Preparing a homogeneous solution or slurry solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. A solution process to
a drying step of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor;
a heat treatment step of heating the precursor in the presence of sulfur vapor to produce a solid electrolyte;
including;
The sulfur vapor is generated by heating elemental sulfur at a temperature above its melting point,
A method for producing a sulfide-based solid electrolyte , wherein the heat treatment step is performed under sulfur reflux. Preparing a homogeneous solution or slurry solution containing at least a lithium element, a phosphorus element, and a sulfur element in an organic solvent, and at least one metal element selected from the group consisting of a silicon element, a germanium element, and a tin element. A solution process to
a drying step of removing the organic solvent from the homogeneous solution or slurry solution to obtain a precursor;
a heat treatment step of heating the precursor in the presence of sulfur vapor to produce a solid electrolyte;
including;
The sulfur vapor is generated by heating elemental sulfur at a temperature above its melting point,
The method for producing a sulfide-based solid electrolyte, wherein the elemental sulfur is placed at a location different from the precursor. The homogeneous solution or slurry solution contains Li ₂ S,P ₂ S ₅ , and SiS ₂ The manufacturing method according to any one of claims 2 to 4, which is prepared from a raw material containing. The manufacturing method according to any one of claims 1 to 5, wherein the sulfide-based solid electrolyte is an LGPS-based solid electrolyte. The manufacturing method according to any one of claims 1 to 6, wherein the metal element contains a silicon element. The manufacturing method according to any one of claims 1 to 7, wherein the heating temperature in the heat treatment step is 250 to 550°C.