Method for producing sulfide-based solid electrolyte and device for producing sulfide-based solid electrolyte

Abstract

A method for producing a sulfide-based solid electrolyte in which a sulfide-based solid electrolyte material is supplied to a heat treatment furnace for heat treatment, the heat treatment furnace comprising: a heating unit for heat treatment of the sulfide-based solid electrolyte material; a rotating member passing through the heating unit; and a pressurizing chamber provided in the sliding part of the rotating member, the pressurizing chamber heating the sulfide-based solid electrolyte material while controlling the pressure of the pressurizing chamber to be higher than the pressure of the heating part and the external air pressure.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a sulfide-based solid electrolyte and an apparatus for manufacturing a sulfide-based solid electrolyte. Background Art

[0002] Lithium-ion secondary batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Conventionally, a liquid electrolyte has been used in lithium-ion secondary batteries. On the other hand, in recent years, all-solid-state lithium-ion batteries using a solid electrolyte as the electrolyte of the lithium-ion secondary battery have attracted attention from the viewpoints of expected improvement in safety, high-speed charging and discharging, and miniaturization of the casing.

[0003] As the solid electrolyte used in the all-solid-state lithium-ion battery, for example, a sulfide-based solid electrolyte can be cited.

[0004] As a method for synthesizing a sulfide-based solid electrolyte, a method of mechanically grinding a raw material for a sulfide-based solid electrolyte, a method of heating and melting to prepare a melt and cooling and solidifying the melt can be cited. However, since the crystal structure of the obtained sulfide-based solid electrolyte is unstable, or sulfur as an impurity adheres to the surface of the sulfide-based solid electrolyte, the performance of the solid electrolyte for secondary batteries is insufficient. Therefore, in order to improve the battery performance of the solid electrolyte, heat treatment or the like is further performed.

[0005] For example, in Patent Document 1, a method for a sulfide-based solid electrolyte is disclosed, in which a sulfide glass obtained by amorphizing a raw material composition by mechanical grinding or the like is heated while being rotated and flowed under atmospheric pressure and reduced pressure less than atmospheric pressure, so that the sulfide glass is crystallized and monomer sulfur mixed as an impurity in the sulfide glass is removed.

[0006] In addition, in Patent Document 2, a method for manufacturing sulfide-based solid electrolyte fine particles is disclosed, in which a coarse particle material such as a sulfide glass obtained by amorphizing a raw material composition by mechanical grinding or the like is pulverized into a fine particle material, and heat treatment is performed while applying physical stimulation to the fine particle material to crystallize it.

[0007] On the other hand, when performing heat treatment using a heat treatment apparatus, in order not to interfere with the operation of the heat treatment apparatus, it is necessary to suppress the adhesion of by-products generated by the heat treatment or the like inside the heat treatment apparatus. Especially in the case of continuous treatment for mass production, the heat treatment apparatus mostly includes a rotating member capable of heating and conveying a processing material. In this case, it is necessary to suppress the part where the driving of the rotating member is hindered by the adhesion of by-products, that is, to suppress the adhesion of by-products or the like to the boundary portion between the rotating member and the fixed member in the heat treatment apparatus and to prevent the rotation of the rotating member.

[0008] As a method for suppressing the adhesion of by-products to a heat treatment apparatus or the like, for example, Patent Document 3 discloses a method for continuously producing lithium sulfide by reacting a lithium raw material with hydrogen sulfide gas. In this method, hydrogen sulfide gas is supplied into the reaction tank from upstream to downstream along the moving direction of the lithium raw material, and from a position more downstream than the position where the lithium raw material is supplied into the reaction tank, thereby suppressing the adhesion of the lithium raw material that has absorbed water as a reaction by-product to a raw material hopper, a raw material supply pipe, or the like.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent No. 7035772 Gazette

[0012] Patent Document 2: Japanese Patent No. 6946791 Gazette

[0013] Patent Document 3: Japanese Patent No. 6718774 Gazette Summary of the Invention

[0014] Patent Documents 1 and 2 disclose a method for removing monomer sulfur as an impurity by heat-treating a sulfide-based solid electrolyte material obtained by mechanical grinding to crystallize it, but do not disclose a method for suppressing the adhesion of the removed sulfur to the manufacturing apparatus.

[0015] Patent Document 3 does not disclose a heat treatment method for the electrolyte or a method for preventing adhesion. In addition, in the method of blowing gas into the reaction tank disclosed in Patent Document 3, the effect of preventing adhesion is exerted directly below the blown gas, but in the peripheral portion, since the surrounding atmosphere is involved, it is difficult to stably suppress adhesion. In addition, there is no mention of suppressing the rotation hindrance of the rotating member caused by the adhesion of the above-mentioned by-products.

[0016] Therefore, an object of the present invention is to provide a method and an apparatus for manufacturing a sulfide-based solid electrolyte, which can suppress the adhesion of sulfur to the boundary portion between the rotating member and the fixed member of the heat treatment apparatus, particularly in the method of heating and transporting a sulfide-based solid electrolyte material using a heat treatment apparatus having a rotating member to manufacture a sulfide-based solid electrolyte, and can stably produce a sulfide-based solid electrolyte having excellent battery performance.

[0017] As a result of intensive research, the present inventors have found that in a method for manufacturing a sulfide-based solid electrolyte by heating and transporting a sulfide-based solid electrolyte material using a heat treatment apparatus having a rotating member, by providing a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixed member and heat-treating the sulfide-based solid electrolyte material while controlling the pressure in the pressurizing chamber to be higher than the pressure in the heating portion or the external gas, the above problems can be solved, and thus the present invention has been completed.

[0018] That is, the present invention relates to the following [1] to [8].

[0019] [1] A method for manufacturing a sulfide-based solid electrolyte, which is a method for manufacturing a sulfide-based solid electrolyte by supplying a sulfide-based solid electrolyte material to a heat treatment apparatus and performing heat treatment.

[0020] The above heat treatment apparatus includes: a heating portion that heat-treats the sulfide-based solid electrolyte material; a rotating member that transports the sulfide-based solid electrolyte material while heating it through the heating portion; a fixed member that is disposed on the end side in the axial direction of the rotating member and is stationary; and a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixed member.

[0021] The sulfide-based solid electrolyte material is heat-treated while controlling the pressure in the pressurizing chamber to be higher than the pressure in the heating portion and the external air pressure.

[0022] [2] The method for manufacturing a sulfide-based solid electrolyte according to the above [1], wherein the sulfide-based solid electrolyte material is obtained by mechanically grinding or heating and melting a sulfide-based solid electrolyte raw material.

[0023] [3] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the oxygen concentration in the pressurizing chamber is 10 volume ppm or more.

[0024] [4] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the heating temperature of the heating portion is 300 °C or more.

[0025] [5] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the pressure difference between the pressure in the pressurizing chamber and the pressure in the heating portion and the external air pressure is 0.1 kPa or more, respectively.

[0026] [6] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the sulfide-based solid electrolyte material is continuously supplied for heat treatment.

[0027] [7] A manufacturing apparatus for a sulfide-based solid electrolyte, comprising:

[0028] A heating unit that performs a heating treatment on a sulfide-based solid electrolyte material;

[0029] A rotating member that conveys while heating the sulfide-based solid electrolyte material through the above-mentioned heating unit;

[0030] A fixing member that is disposed on the end side in the axial direction of the rotating member and is stationary; and

[0031] A pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member.

[0032] [8] The manufacturing apparatus for a sulfide-based solid electrolyte according to the above [7], further comprising an oxygen supply unit that supplies oxygen to the pressurizing chamber.

[0033] According to the present invention, in a method for manufacturing a sulfide-based solid electrolyte in which a sulfide-based solid electrolyte material is supplied to a heat treatment apparatus for heating treatment, by making the heat treatment apparatus have: a heating unit that performs a heating treatment on a sulfide-based solid electrolyte material; a rotating member that conveys while heating the sulfide-based solid electrolyte material through the heating unit; a fixing member that is disposed on the end side in the axial direction of the rotating member and is stationary; and a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member, and while controlling the pressure of the pressurizing chamber to be higher than the pressure of the heating unit or the external gas, performing a heating treatment on the sulfide-based solid electrolyte material, it is possible to prevent gas that hinders production from flowing into the heating unit, and suppress the adhesion of sulfur that hinders the rotation of the rotating member to the above-mentioned boundary portion due to the adhesion of sulfur. Thereby, a method and an apparatus for manufacturing a sulfide-based solid electrolyte capable of stably producing a sulfide-based solid electrolyte with excellent battery performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is an example of a flowchart of a method for manufacturing a sulfide-based solid electrolyte according to an embodiment of the present invention.

[0035] Figure 2 is a side cross-sectional schematic view showing an example of a manufacturing apparatus for a sulfide-based solid electrolyte according to a first embodiment of the present invention.

[0036] Figure 3 is a top cross-sectional schematic view showing an example of a heating unit and its peripheral portion in a manufacturing apparatus for a sulfide-based solid electrolyte according to a first embodiment of the present invention.

[0037] Figure 4It is a top cross-sectional schematic diagram showing another example of the heating part and its peripheral part in the manufacturing apparatus of the sulfide-based solid electrolyte according to the first embodiment of the present invention.

[0038] Figure 5 It is a top cross-sectional schematic diagram showing another example of the heating part and its peripheral part in the manufacturing apparatus of the sulfide-based solid electrolyte according to the first embodiment of the present invention.

[0039] Figure 6 It is a top cross-sectional schematic diagram showing an example of the sliding part of the rotating member and the pressurizing chamber in the manufacturing apparatus of the sulfide-based solid electrolyte according to the first embodiment of the present invention.

[0040] Figure 7 It is a side cross-sectional schematic diagram showing an example of the manufacturing apparatus of the sulfide-based solid electrolyte according to the second embodiment of the present invention.

[0041] Figure 8 It is a side cross-sectional schematic diagram showing an example of the sliding part of the rotating member and the pressurizing chamber in the manufacturing apparatus of the sulfide-based solid electrolyte according to the second embodiment of the present invention.

[0042] Figure 9 It is a side cross-sectional schematic diagram showing an example of the manufacturing apparatus of the sulfide-based solid electrolyte according to the third embodiment of the present invention.

[0043] Figure 10 It is a side cross-sectional schematic diagram showing an example of the sliding part of the rotating member and the pressurizing chamber in the manufacturing apparatus of the sulfide-based solid electrolyte according to the third embodiment of the present invention. Detailed Description of the Invention

[0044] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value. In addition, in the following drawings, components and parts that perform the same function are denoted by the same reference numerals, and repeated descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematically shown for clearly explaining the present invention, and do not necessarily accurately represent the dimensions or scales of actual devices, etc.

[0045] 〔Manufacturing Method of Sulfide-Based Solid Electrolyte〕

[0046] A method for manufacturing a sulfide-based solid electrolyte according to an embodiment of the present invention (hereinafter also referred to as this manufacturing method) is characterized in that it is a method for manufacturing a sulfide-based solid electrolyte in which a sulfide-based solid electrolyte material is supplied to a heat treatment device for heat treatment. The heat treatment device has: a heating unit that heat-treats the sulfide-based solid electrolyte material; a rotating member that conveys while heating the sulfide-based solid electrolyte material through the heating unit; a fixing member that is disposed on the end side in the axial direction of the rotating member and does not move; and a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member, and heat-treats the sulfide-based solid electrolyte material while controlling the pressure in the pressurizing chamber to be higher than the pressure in the heating unit and the external air pressure.

[0047] Figure 1 An example of a flowchart showing this manufacturing method is shown. In this manufacturing method, first, a sulfide-based solid electrolyte material is supplied to a heat treatment device (step S1), and while pressurizing the pressurizing chamber, the sulfide-based solid electrolyte material is heated and conveyed through the heating unit (step S2), the heat-treated product is cooled (step S3), the heat-treated product is taken out from the heat treatment device (step S4), and a sulfide-based solid electrolyte is obtained (step S5).

[0048] Here, step S3 can be performed after step S4. That is, it is possible to supply a sulfide-based solid electrolyte material to a heat treatment device, heat-treat the sulfide-based solid electrolyte material in a heating unit, take out the heat-treated product from the heat treatment device, and then cool it to obtain a sulfide-based solid electrolyte.

[0049] As described below, it is preferable to continuously perform the above steps S1 to S5. When this continuous manufacturing method is adopted, the effects of the present invention are further improved.

[0050] <Sulfide-based solid electrolyte material>

[0051] In this manufacturing method, the sulfide-based solid electrolyte material (hereinafter sometimes referred to as this material) refers to a material that obtains a desired sulfide-based solid electrolyte by heat treatment at a specified temperature. For example, a sulfide-based solid electrolyte in a raw form having sulfur as an impurity on its surface and whose crystal structure is homogenized by removing the sulfur in the form of a gas or the like through heat treatment can be cited. That is, this material is a precursor of the finally obtained sulfide-based solid electrolyte before heat treatment. This material is different from the sulfide-based solid electrolyte raw material described later. When this material is a sulfide-based solid electrolyte with sulfur as an impurity attached to its surface, the excess sulfur on the surface that hinders battery performance can be removed in the form of a gas through heat treatment, and the battery performance when used as a solid electrolyte for a secondary battery can be improved.

[0052] It should be noted that the above sulfide-based solid electrolyte material can be amorphous and can contain an amorphous phase. This material with an unstable crystal structure can homogenize the crystal structure through heat treatment, improve the ionic conductivity, and enhance the battery performance when used as a solid electrolyte for secondary batteries.

[0053] In this manufacturing method, a commercially available sulfide-based solid electrolyte material can be used as the sulfide-based solid electrolyte material, or a material manufactured from sulfide-based solid electrolyte raw materials can also be used.

[0054] The sulfide-based solid electrolyte material is preferably obtained by mechanically grinding or heat-melting the sulfide-based solid electrolyte raw materials.

[0055] (Sulfide-based solid electrolyte raw materials)

[0056] The sulfide-based solid electrolyte raw materials (hereinafter sometimes referred to as these raw materials) refer to the constituent raw materials of the sulfide-based solid electrolyte used to obtain the desired sulfide-based solid electrolyte. Generally, multiple types of these raw materials are mixed and used. There is a difference from the above-mentioned sulfide-based solid electrolyte materials. Various raw materials can be used as these raw materials.

[0057] As these raw materials, commercially available sulfide-based solid electrolyte raw materials can be used, or substances obtained by manufacturing sulfide-based solid electrolyte raw materials from materials can also be used. In addition, these sulfide-based solid electrolyte raw materials can be further subjected to known pretreatment.

[0058] The sulfide-based solid electrolyte raw materials are specifically described below. As the sulfide-based solid electrolyte raw materials, an alkali metal element (R) and a sulfur element (S) are usually contained.

[0059] As the alkali metal element (R), lithium element (Li), sodium element (Na), potassium element (K), etc. can be cited. Among them, lithium element (Li) is preferred. As the alkali metal element (R), substances (components) containing the alkali metal element such as the alkali metal element in its elemental form or compounds containing the alkali metal element can be appropriately combined and used. Among them, as the lithium element, substances (components) containing Li such as Li in its elemental form or compounds containing Li can be appropriately combined and used.

[0060] As substances containing lithium element (Li), for example, lithium sulfide (Li2S), lithium iodide (LiI), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium oxide (Li2O), lithium hydroxide (LiOH) and other lithium compounds, metallic lithium, etc. can be cited. As substances containing lithium element (Li), from the perspective of obtaining the sulfide material, lithium sulfide is preferably used.

[0061] As the sulfur element (S), a substance (component) containing S, such as a simple substance of S or a compound containing S, etc., can be used in combination as appropriate.

[0062] Examples of substances containing elemental sulfur (S) include phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5), other sulfur compounds containing phosphorus, elemental sulfur, and compounds containing sulfur.

[0063] Examples of compounds containing sulfur include H2S, CS2, iron sulfide (FeS, Fe2S3, FeS2, Fe 1-x S, etc.), bismuth sulfide (Bi2S3), copper sulfide (CuS, Cu2S, Cu 1-x S, etc.).

[0064] From the viewpoint of obtaining a sulfide material, the substance containing elemental sulfur (S) is preferably phosphorus sulfide, and more preferably phosphorus pentasulfide (P2S5).

[0065] These substances may be used alone or in combination of two or more. Phosphorus sulfide may be considered as a compound serving as both a substance containing S and a substance containing P described later.

[0066] From the viewpoint of improving the ionic conductivity of the obtained sulfide-based solid electrolyte, the raw material preferably further contains phosphorus (P). As phosphorus (P), substances (components) containing P such as a single substance of P or a compound containing P can be used in appropriate combination.

[0067] Examples of substances containing phosphorus element (P) include phosphorus sulfides such as phosphorus trisulfide (P2S3) and phosphorus pentasulfide (P2S5), phosphorus compounds such as sodium phosphate (Na3PO4), and elemental phosphorus.

[0068] As the substance containing phosphorus element (P), from the viewpoint of further exerting the effect of the present invention, highly volatile phosphorus sulfide is preferred, and phosphorus pentasulfide (P2S5) is more preferred. These substances may be used alone or in combination of two or more.

[0069] This raw material can be obtained as a mixed raw material by appropriately mixing the above-mentioned substances according to the composition of the target sulfide-based solid electrolyte, for example. The mixing ratio is not particularly limited. For example, from the perspective of improving the ionic conductivity of the obtained sulfide-based solid electrolyte, the molar ratio S / R of sulfur element (S) to alkali metal element (R) in this raw material is preferably 0.65 / 0.35 or less, and more preferably 0.5 / 0.5 or less. In addition, the mixed raw material is preferably obtained by mixing the substances used in the mixing according to a prescribed stoichiometric ratio.

[0070] As a method for the above mixing, for example, mixing using a mortar, mixing using a medium such as a planetary ball mill, and medium-free mixing such as a needle mill, a powder blender, and pneumatic mixing can be cited.

[0071] As an example of a preferred combination of the alkali metal element and the sulfur element contained in the present raw material, a combination of Li2S and P2S5 can be cited. When combining Li2S and P2S5, the molar ratio of Li to P, Li / P, is preferably 40 / 60 or more, more preferably 50 / 50 or more. In addition, the molar ratio of Li to P, Li / P, is preferably 88 / 12 or less. Further, the molar ratio of Li to P, Li / P, is preferably 40 / 60 to 88 / 12, more preferably 50 / 50 to 88 / 12. By adjusting the mixing ratio such that P2S5 is less than Li2S, it is easy to suppress the volatilization of the sulfur component and the phosphorus component during the heat treatment due to the boiling point of P2S5 being lower than the melting point of Li2S.

[0072] On the other hand, since lithium sulfide is expensive, from the viewpoint of suppressing the manufacturing cost of the sulfide solid electrolyte, lithium compounds other than lithium sulfide, metallic lithium, etc. can be used. Specifically, in this case, in the present raw material, as the substance containing Li, it is preferable to contain one or more selected from metallic lithium, lithium iodide (LiI), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium oxide (Li2O), and lithium hydroxide (LiOH). These substances can be used alone or in combination of two or more.

[0073] The present raw material may contain other substances (compounds, etc.) in addition to the above substances according to the composition of the target sulfide solid electrolyte or as an additive, etc.

[0074] For example, when manufacturing a sulfide solid electrolyte containing a halogen element such as F, Cl, Br, or I, the present raw material preferably contains a halogen element (Ha). In this case, the present raw material preferably contains a compound containing a halogen element.

[0075] As the compound containing a halogen element, lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, boron halides, etc. can be cited. As the compound containing a halogen element, from the viewpoint of the reactivity of the raw material, lithium halides are preferred, and LiCl, LiBr, and LiI are more preferred. These compounds can be used alone or in combination of two or more.

[0076] It should be noted that alkali metal halides such as lithium halide can be compounds containing alkali metal elements such as Li. When the present raw material contains an alkali metal halide, a part or all of the alkali metal elements such as Li in the present raw material can be derived from the alkali metal halide such as lithium halide.

[0077] When the raw material contains a halogen element (Ha) and a phosphorus element (P), from the viewpoint of improving the ionic conductivity of the obtained sulfide-based solid electrolyte, etc., the molar equivalent of Ha to P in the raw material is preferably 0.2 molar equivalents or more, more preferably 0.5 molar equivalents or more. Further, from the viewpoint of the stability of the obtained sulfide-based solid electrolyte, the molar equivalent of Ha is preferably 4 molar equivalents or less, more preferably 3 molar equivalents or less.

[0078] When the sulfide-based solid electrolyte material obtained from the raw material is amorphous, from the viewpoint of improving the ease of formation of the amorphous phase, the raw material also preferably contains sulfides such as SiS2, B2S3, GeS2, and Al2S3. By making it easy to form the amorphous phase, in the case of obtaining an amorphous material by rapid cooling, even if the cooling rate is reduced, an amorphous sulfide-based solid electrolyte material can be obtained, and the equipment load can be reduced.

[0079] Further, from the viewpoint of imparting moisture resistance to the sulfide-based solid electrolyte, etc., oxides such as SiO2, B2O3, GeO2, Al2O3, and P2O5 are also preferably contained. These compounds can be used alone or in combination of two or more.

[0080] It should be noted that the above sulfides or oxides can be contained in the raw material, and in the case of preparing a sulfide-based solid electrolyte material by heat melting, they can also be additionally added when the raw material is heat melted. Further, the addition amount of the above sulfides or oxides is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, relative to the total amount of the raw material. Further, the addition amount of the above sulfides or oxides is preferably 50 mass% or less, more preferably 40 mass% or less.

[0081] In addition, when the sulfide-based solid electrolyte material obtained from the raw material contains a crystal layer, the raw material can contain compounds that become crystal nuclei, such as oxides, oxynitrides, nitrides, carbides, other chalcogen compounds, and halides.

[0082] (Mechanical grinding)

[0083] A sulfide-based solid electrolyte material can be obtained by mechanically grinding the above-mentioned sulfide-based solid electrolyte raw material.

[0084] Mechanical grinding is not particularly limited as long as it is a method of mixing while imparting mechanical energy to the sulfide-based solid electrolyte raw material. For example, planetary mills, ball mills, vibration mills, turbo mills, mechanical fusion machines, disk mills, etc. can be cited.

[0085] The processing conditions of mechanical grinding can be set in a manner that the desired sulfide-based solid electrolyte material can be obtained. For example, when a planetary ball mill is used, a sulfide-based solid electrolyte raw material and a grinding ball are added to a container and processed at a specified rotation speed and time. Generally speaking, the higher the rotation speed, the faster the generation rate of the sulfide-based solid electrolyte material, the longer the processing time, and the higher the conversion rate from the sulfide-based solid electrolyte raw material to the sulfide-based solid electrolyte material.

[0086] The rotation speed of the bottom plate when the planetary ball mill is used is preferably 200 rpm to 500 rpm, for example. The treatment time when the planetary ball mill is used is, for example, 1 hour to 100 hours, and preferably 1 hour to 50 hours.

[0087] The material and size of the container and grinding balls used in the ball mill are not particularly limited, and conventionally known conditions can be used. Examples of the material include alumina, zirconia, glass, silicon nitride, etc. The diameter of the grinding balls is, for example, 1 mm to 20 mm.

[0088] Mechanical grinding can be dry mechanical grinding or wet mechanical grinding. The liquid used in wet mechanical grinding is preferably a liquid having the property of not generating hydrogen sulfide in the reaction with the sulfide-based solid electrolyte raw material. After mechanical grinding, the sulfide-based solid electrolyte material is preferably dried. As a drying method, for example, a drying method using a hot plate can be cited.

[0089] (Heating and melting)

[0090] The sulfide-based solid electrolyte material can be obtained by heating and melting the above-mentioned sulfide-based solid electrolyte raw material.

[0091] In the heating and melting method, first, a sulfide-based solid electrolyte raw material is heated to a temperature at which the sulfide-based solid electrolyte raw material melts to obtain a melt, and the obtained melt is cooled and solidified to obtain a sulfide-based solid electrolyte material.

[0092] ·Heating and melting of sulfide-based solid electrolyte raw materials

[0093] The heating and melting of the sulfide-based solid electrolyte raw material is preferably carried out in a gas atmosphere containing sulfur. By heating and melting the raw material in a gas atmosphere containing sulfur, sulfur is introduced into the melt. As a result, the volatilization of sulfur during heating can be suppressed, so the composition of the obtained sulfide-based solid electrolyte material can be appropriately controlled. The gas containing sulfur is, for example, a compound containing sulfur such as sulfur gas, hydrogen sulfide gas, carbon disulfide gas, or a gas containing sulfur.

[0094] The temperature for heating and melting is not particularly limited. From the perspective of homogenizing the melt in a short time, it is preferably 600 °C or higher, more preferably 630 °C or higher, and further preferably 650 °C or higher. Additionally, from the perspective of suppressing deterioration or decomposition of the components in the melt due to heating, the temperature for heating and melting is preferably 1000 °C or lower, more preferably 950 °C or lower, further preferably less than 900 °C, and particularly preferably less than 800 °C. Moreover, the temperature for heating and melting is preferably 600 °C or higher and less than 900 °C.

[0095] The time for heating and melting to obtain the melt is not particularly limited. For example, it can be 0.5 hours or longer, it can be 1 hour or longer, and it can be 2 hours or longer. Additionally, for the time of heating and melting, the time of heating and melting can be extended within the allowable range of deterioration or decomposition caused by heating of the components in the melt. As a practical range, the time for heating and melting is preferably 100 hours or shorter, more preferably 50 hours or shorter, and further preferably 25 hours or shorter.

[0096] The pressure during heating and melting is not particularly limited. For example, normal pressure or slightly increased pressure is preferred, and normal pressure is more preferred.

[0097] During heating and melting, from the perspective of preventing side reactions with water vapor or oxygen, etc., the dew point in the furnace is preferably -20 °C or lower, and the lower limit is not particularly limited and is usually -80 °C or higher. Additionally, the oxygen concentration is preferably 1000 volume ppm or lower.

[0098] · Cooling of the melt

[0099] Next, the obtained melt is cooled and solidified to obtain a sulfide-based solid electrolyte material.

[0100] Cooling can be carried out by a known method, and the method is not particularly limited. As a more specific method of cooling, for example, a method of flowing the melt onto a plate-like body made of carbon, etc. for cooling; a method of flowing into a narrow gap and thinly forming, represented by the twin-roll method; a gas atomization method, etc.

[0101] When flowing the melt onto a plate-like body for cooling, from the perspective of improving the cooling efficiency, it is preferred that the thickness of the melt after flowing and the obtained solid is thinner. Specifically, the thickness is preferably 10 mm or less, and more preferably 5 mm or less. The lower limit of the thickness is not particularly limited and can be 0.01 mm or more, and can be 0.02 mm or more.

[0102] When the solid is poured into a narrow gap and thinly molded, the cooling efficiency is excellent, and a flaky material, a fibrous material, a powdery material, etc. can be obtained. The obtained solid is crushed into a size that is easy to handle, etc., and obtained in an arbitrary shape. Among them, it is easier to recycle the solid in a block, so it is preferred. The block also includes the case of a plate, a flaky or a fibrous shape.

[0103] In the case of the gas atomization method, the obtained melt is discharged from the furnace while the gas is sprayed, thereby cooling and solidifying the melt to obtain a sulfide-based solid electrolyte material. The obtained sulfide-based solid electrolyte material is in a powder form. As the gas sprayed in the gas atomization method, an inert gas such as nitrogen or argon is preferably used.

[0104] From the viewpoint of maintaining the composition obtained by heating and melting, the cooling rate is preferably 0.01°C / sec or more, more preferably 0.05°C / sec or more, and further preferably 0.1°C / sec or more. In addition, the upper limit of the cooling rate is not particularly limited, and the cooling rate of the twin-roll method, which is generally considered to have a fast cooling rate, is 10 7 ℃ / second or less.

[0105] Here, when the obtained solid is intended to be an amorphous sulfide-based solid electrolyte material, it is preferred to rapidly cool the melt obtained by heating and melting to obtain a solid. Specifically, the cooling rate during rapid cooling is preferably 10°C / second or more, more preferably 100°C / second or more, further preferably 500°C / second or more, and further preferably 700°C / second or more. In addition, the upper limit of the cooling rate is not particularly limited, and the cooling rate of the double roll method, which is generally considered to have a fast rapid cooling rate, is 10 7 ℃ / second or less.

[0106] On the other hand, it is also possible to perform slow cooling during cooling to crystallize at least a portion of the solid, thereby obtaining a sulfide-based solid electrolyte material having a specific crystal structure or a sulfide-based solid electrolyte material consisting of a crystalline phase and an amorphous phase. The cooling rate during slow cooling is preferably 0.01°C / second or more, more preferably 0.05°C / second or more. In addition, the cooling rate is preferably 500°C / second or less, more preferably 450°C / second or less. The cooling rate may be less than 10°C / second, and may be 5°C / second or less. It should be noted that the cooling rate may be appropriately adjusted according to the conditions of crystallization.

[0107] The process may further include a step of subjecting the sulfide-based solid electrolyte material obtained by cooling the melt to a known post-treatment. Examples of the post-treatment step include a step of pulverizing the material from the viewpoint of obtaining a desired shape.

[0108] <Sulfide-based solid electrolyte production device>

[0109] Here, a manufacturing apparatus for a sulfide-based solid electrolyte used in this manufacturing method (hereinafter also referred to as this manufacturing apparatus or heat treatment apparatus) will be described.

[0110] This manufacturing apparatus is a heat treatment apparatus, comprising: a heating unit that heat-treats a sulfide-based solid electrolyte material; a rotating member that conveys the sulfide-based solid electrolyte material while heating it through the heating unit; a fixing member that is disposed on the end side in the axial direction of the rotating member and has a fixed position; and a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member.

[0111] In this manufacturing apparatus, as long as the sulfide-based solid electrolyte material is heated through the heating unit and conveyed through the rotating member, there is no particular limitation on the arrangement of the heating unit or the rotating member. The method of conveying the sulfide-based solid electrolyte material by the rotating member is also not particularly limited. The sulfide-based solid electrolyte material can be conveyed by arranging it on the upper part of the rotating member like the conveying roller described later, can be conveyed by introducing the sulfide-based solid electrolyte material into the interior of the rotating member like the furnace core tube described later, or can be conveyed by using the conveying blades provided on the rotating member like the drying furnace described later. The rotating member is provided so as to penetrate the heating unit.

[0112] This manufacturing apparatus includes a fixing member that is disposed on the end side in the axial direction of the rotating member and has a fixed position. The fixing member is fixedly fixed to a stable place such as a base, and is disposed on one side or both ends of the rotating member or in the vicinity thereof, and the entire rotating member maintains a freely rotatable state.

[0113] In this manufacturing apparatus, in order to keep the entire rotating member in a freely rotatable state, there is a gap at the boundary portion between the rotating member and the fixing member, or this boundary portion becomes a sliding portion where the rotating member and the fixing member slide while rubbing against each other.

[0114] This manufacturing apparatus includes a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member. Conventionally, if a sulfide-based solid electrolyte material containing sulfur as an impurity is heat-treated, sulfur gas is generated. If the generated sulfur gas flows into the above-mentioned boundary portion, sulfur becomes below the melting point at the low-temperature boundary portion, and sulfur adheres to the boundary portion, causing a problem of hindering the rotation of the rotating member. However, in this manufacturing apparatus, by providing a pressurizing chamber that pressurizes the boundary portion between the rotating member and the fixing member, and while controlling the pressure of the pressurizing chamber to be higher than the pressure of the heating unit and the external air pressure, the heat treatment of the sulfide-based solid electrolyte material is performed. Thereby, it is possible to suppress the rotation hindrance caused by sulfur adhering to the boundary portion, and it is possible to perform the heat treatment while preventing the inflow of gas that hinders production from the external gas.

[0115] In this boundary part, from the viewpoints such as the heat resistance of the sealing material used, it is preferably lower than the temperature of the heating part. In this case, the above-mentioned boundary part is not included in the heating part.

[0116] The heat treatment and the pressurization of the pressurization chamber will be described in detail below.

[0117] (Heat treatment)

[0118] In this manufacturing method, a sulfide-based solid electrolyte material is supplied to a heat treatment device, and the sulfide-based solid electrolyte material is heat-treated by a heating part. By heat-treating the sulfide-based solid electrolyte material, sulfur attached to the surface of the sulfide-based solid electrolyte material is removed in the form of a gas, and in addition, the crystal structure of the sulfide-based solid electrolyte material is homogenized, so that the performance of the solid electrolyte of the secondary battery is improved.

[0119] It should be noted that "crystal structure homogenization" means that even if further heat treatment is carried out at a specified temperature for a long time, the crystal structure does not change and reaches an equilibrium state.

[0120] From the viewpoints of removing sulfur attached to the surface of the sulfide-based solid electrolyte material and homogenizing the crystal structure of the sulfide-based solid electrolyte material, the heating temperature of the heating part is preferably 300 °C or higher, more preferably 325 °C or higher, and further preferably 350 °C or higher. In addition, from the viewpoints of suppressing deterioration or decomposition caused by heating of the components in the sulfide-based solid electrolyte material, etc., the heating temperature of the heating part is preferably 500 °C or lower, more preferably 475 °C or lower, and further preferably 450 °C or lower. In addition, it is preferably 300 °C to 500 °C.

[0121] The means of heating in the heating part of the heat treatment device can be appropriately used by the methods known heretofore according to the type of the heat treatment device. For example, heaters such as Kanthal heaters, SiC heaters, and carbon heaters that heat an object by passing an electric current through a heating material, heaters such as halogen heaters that perform radiant heating, and high-frequency induction heating devices can be appropriately used.

[0122] The pressure of the heating part during the heat treatment is not particularly limited. For example, normal pressure or slightly increased pressure is preferred, and normal pressure is more preferred.

[0123] During the heat treatment, from the viewpoint of preventing side reactions with water vapor or oxygen, etc., the dew point of the atmosphere in the heating part is preferably -20 °C or lower, and the lower limit is not particularly limited and is usually -80 °C or higher. In addition, the oxygen concentration is preferably 1000 volume ppm or lower.

[0124] The heating part of the heat treatment device is preferably an inert gas atmosphere such as nitrogen, argon, or helium.

[0125] For example, when the atmosphere inside the furnace is pre-replaced with an inert gas atmosphere and a sulfide-based solid electrolyte material is introduced into the heat treatment apparatus, the inert gas atmosphere inside the apparatus can be enhanced by replacing the purge section near the introduction port with an inert gas or the like.

[0126] (Pressurization of the pressurization chamber)

[0127] In this manufacturing method, while controlling the pressure of the pressurization chamber to be higher than the pressure of the heating section and the external air pressure, the heat treatment of the sulfide-based solid electrolyte material is carried out. By controlling the pressure of the pressurization chamber to be higher than the pressure of the heating section and the external air pressure, the gas supplied to the pressurization chamber leaks locally from the pressurization chamber to the boundary section. Therefore, it is possible to prevent the inflow of sulfur gas from the heating section to the boundary section and the adhesion of sulfur, and to prevent the inflow of production-inhibiting gas from the external gas to the heating section.

[0128] From the viewpoint of preventing the inflow of sulfur gas from the heating section to the boundary section and preventing the inflow of production-inhibiting gas from the external gas to the heating section, as the pressure of the pressurization chamber, the pressure differences from the pressure of the heating section and the external air pressure are preferably 0.1 kPa or more, more preferably 0.25 kPa or more, and further preferably 0.5 kPa or more. In addition, the upper limit is not specifically limited. From the viewpoints of continuous operation stability and realistic gas spraying cost, it is preferably 100 kPa or less, more preferably 75 kPa or less, and further preferably 50 kPa or less. In addition, it is preferably 0.1 kPa to 100 kPa.

[0129] The above-mentioned pressure difference is preferably 0.1 kPa to 100 kPa, more preferably 0.25 kPa to 75 kPa, and further preferably 0.5 kPa to 50 kPa.

[0130] As the pressurized gas supplied to the pressurization chamber, an inert gas such as nitrogen or argon is preferably used.

[0131] In addition to the inert gas, the above-mentioned pressurized gas preferably contains oxygen. That is, this manufacturing apparatus preferably includes an oxygen supply section for supplying oxygen to the pressurization chamber.

[0132] Oxygen is preferably adjusted so that the oxygen concentration in the pressurization chamber becomes 10 volume ppm or more, more preferably 25 volume ppm or more, and further preferably 50 volume ppm or more. By making the oxygen concentration in the pressurization chamber 10 volume ppm or more, when the sulfur gas generated in the heating section flows into the vicinity of the boundary section, it reacts with the oxygen in the pressurized gas leaked from the pressurization chamber to the boundary section and becomes sulfur dioxide with a low melting point, and the adhesion of sulfur to the boundary section can be further suppressed.

[0133] In addition, from the viewpoint of obtaining a sulfide-based solid electrolyte with a desired composition by suppressing the reaction between oxygen and the sulfide-based solid electrolyte material, the oxygen concentration in the pressurization chamber is preferably 1000 volume ppm or less, more preferably 750 volume ppm or less, and still more preferably 500 volume ppm or less.

[0134] The oxygen concentration in the pressurization chamber is preferably 10 volume ppm to 1000 volume ppm, more preferably 25 volume ppm to 750 volume ppm, and still more preferably 50 volume ppm to 500 volume ppm.

[0135] From the viewpoint of preventing side reactions between the sulfide-based solid electrolyte material and water vapor, the dew point of the above-mentioned pressurized gas is preferably less than -30°C, more preferably less than -40°C, and still more preferably less than -50°C in terms of the dew point at atmospheric pressure.

[0136] The temperature of the pressurized gas is not particularly limited, for example, it is 100°C or less, and preferably at room temperature.

[0137] In this manufacturing method, since the heat treatment device has a rotating member that conveys the sulfide-based solid electrolyte material while heating it through the heating unit, the sulfide-based solid electrolyte material can be continuously supplied for heat treatment, and the sulfide-based solid electrolyte can be mass-produced. In addition, the effects of the present invention are further improved.

[0138] (Cooling and taking out)

[0139] The heat-treated product obtained by performing heat treatment with the heating unit while pressurizing the pressurization chamber under the above conditions is preferably taken out of the heat treatment device after cooling. That is, when the raw material inlet side of the heat treatment device is the upstream and the discharge port side is the downstream, it is preferably provided with a cooling unit for cooling the heat-treated product on the downstream side of the heat treatment device relative to the heating unit. The heat-treated product conveyed from the heating unit by the rotating member is cooled in the cooling unit and discharged from the heat treatment device.

[0140] In this way, it is preferable to obtain a sulfide-based solid electrolyte by continuously performing the input, heat treatment, cooling, and taking out of the sulfide-based solid electrolyte material.

[0141] When the heat treatment device does not have a cooling unit, the heat-treated product can be cooled after being discharged from the heat treatment device.

[0142] As a cooling means, natural air cooling, water cooling, gas spray cooling, etc. can be appropriately used.

[0143] The cooling rate is preferably 0.01°C / second or more, more preferably 0.025°C / second or more, and still more preferably 0.05°C / second or more, for example. In addition, the upper limit value of the cooling rate is not particularly limited, for example, it is 10°C / second or less.

[0144] The manufacturing apparatus is not particularly limited as long as it has the above-described configuration. For example, as the heat treatment apparatus, a known apparatus having a heating unit that has been conventionally used for heat-treating a solid electrolyte material can be appropriately used, and the material and size can also be arbitrarily selected.

[0145] Among them, it is preferable to include a conveyance mechanism for a sulfide-based solid electrolyte material, and a heat treatment apparatus capable of continuously heat-treating the sulfide-based solid electrolyte material. For example, a roller hearth furnace, a rotary kiln, a stirring dryer, etc. can be cited. Hereinafter, embodiments of the manufacturing apparatus of the furnace having each form will be specifically described.

[0146] (Manufacturing apparatus for sulfide-based solid electrolyte according to the first embodiment)

[0147] Refer to Figures 2 to 6 The first embodiment of the manufacturing apparatus will be described. In the first embodiment, the manufacturing apparatus has a roller hearth furnace.

[0148] Figure 2 FIG. is a side cross-sectional schematic view showing an example of the manufacturing apparatus of the roller hearth furnace type. Figure 3 FIG. is a top cross-sectional schematic view showing an example of the heating unit and its peripheral portion in the manufacturing apparatus of the roller hearth furnace type. Figure 4 , Figure 5 FIG. is a top cross-sectional schematic view showing another example of the heating unit and its peripheral portion in the manufacturing apparatus of the roller hearth furnace type. Figure 6 FIG. is a top cross-sectional schematic view showing an example of the boundary portion of the rotating member and the pressurizing chamber in the manufacturing apparatus of the roller hearth furnace type.

[0149] Figure 2 In FIG., the manufacturing apparatus 1 of the roller hearth furnace type includes a heat treatment furnace 2 and conveyance rollers 5 for conveying a sulfide-based solid electrolyte material. The heat treatment furnace 2 includes a heating unit 3 for heat-treating the sulfide-based solid electrolyte material and a cooling unit 4.

[0150] Figure 3 In FIG., the conveyance rollers 5 are provided so as to penetrate the heating unit 3 of the heat treatment furnace 2. That is, in the manufacturing apparatus 1, the conveyance rollers 5 are rotating members provided so as to penetrate the heating unit 3.

[0151] The manufacturing apparatus 1 has a boundary portion 9 between the conveying roller 5 (rotating member side) and the furnace wall 8 (fixed member side) of the heat treatment furnace 2. A gap for enabling the rotation of the conveying roller 5 exists in the boundary portion 9. The manufacturing apparatus 1 is provided with a pressurizing chamber 10 for pressurizing the boundary portion 9 from the outside of the heat treatment furnace 2. From the viewpoint of being able to pressurize the boundary portion 9, the smaller the width of the above-mentioned gap, the better, preferably 10 mm or less, more preferably 5 mm or less, and still more preferably 1 mm or less. In addition, as long as the conveying roller 5 can slide, there is no limit to the lower limit value of the width of the gap. The dimensions of the width of the above-mentioned gap do not have to be the same, and it is no problem even if there are some places with the minimum gap. In addition, as long as the gap of the above-mentioned boundary portion 9 can enable the rotation of the conveying roller 5 and has a through portion, its mechanism form is not limited. The gap of the through portion can be narrowed to cause friction between the components.

[0152] The pressurizing chamber 10 has no limitation on its installation method as long as it is installed in such a way as to pressurize the boundary portion 9 from the outside of the heat treatment furnace 2. Figure 3 In the manufacturing apparatus 1, the pressurizing chamber is installed in such a way as to pressurize the plurality of existing boundary portions 9 independently, but it can also be, for example, Figure 4 , Figure 5 as shown, the pressurizing chamber is installed in such a way as to pressurize a plurality of boundary portions 9 together. As Figure 5 shown, the pressurizing chamber can be installed in such a way as to cover the entire peripheral portion of the conveying roller 5 including the roller bearings 11a, 11b that rotatably support the conveying roller 5 or the drive motor 12 for rotating the conveying roller 5.

[0153] Hereinafter, an example of the manufacturing method of the sulfide-based solid electrolyte when using the manufacturing apparatus 1 of the roller hearth furnace type will be described.

[0154] The sulfide-based solid electrolyte material charged into the container is introduced from the inlet 6 of the heat treatment furnace 2 and conveyed to the heating section 3 using the conveying roller 5. When the sulfide-based solid electrolyte material is preferably introduced after previously replacing the atmosphere inside the heat treatment furnace 2 with an inert gas, the purge section (not shown) provided near the inlet 6 of the heat treatment furnace 2 is filled with an inert gas or the like and then the sulfide-based solid electrolyte material is introduced.

[0155] The sulfide-based solid electrolyte material conveyed to the heating section 3 by the conveying roller 5 is heat-treated in the heating section 3. The preferred conditions for the heat treatment are as described above. At this time, the heat treatment is performed while controlling the pressure in the pressurizing chamber 10 to be higher than the pressure in the heating section 3 and the external air pressure. The preferred conditions for pressurization are as described above.

[0156] As Figure 6As shown, the pressurization of the pressurization chamber can be performed by supplying pressurized gas from the pressurized gas supply port 13 provided in the pressurization chamber 10. For example, gas is supplied from a gas supply unit (not shown) to the pressurized gas supply port 13 through a pipe (not shown).

[0157] Preferably, an oxygen supply unit (not shown) for supplying oxygen is provided, and a gas containing oxygen is supplied to the pressurization chamber 10. The gas containing oxygen is, for example, a mixed gas prepared by mixing oxygen supplied from the oxygen supply unit and an inert gas supplied from an inert gas supply unit (not shown) in a pipe connecting each supply unit and the pressurized gas supply port 13, and is supplied to the pressurization chamber 10 from the pressurized gas supply port 13. In addition, for example, oxygen supplied from the oxygen supply unit and an inert gas supplied from the inert gas supply unit can be supplied to the pressurization chamber 10 separately from a plurality of pressurized gas supply ports 13.

[0158] If the sulfide-based solid electrolyte material is heat-treated in the heating unit 3, sulfur attached to the surface of the sulfide-based solid electrolyte material is vaporized. The vaporized sulfur is cooled on the furnace wall 8 or the boundary portion 9 where the temperature is lower than that of the heating unit 3, so sulfur adheres to these portions. In this manufacturing method, by pressurizing the pressurization chamber 10, the gas supplied to the pressurization chamber leaks to the boundary portion 9, so that it is possible to suppress the adhesion of sulfur to the boundary portion 9 or to suppress the inflow of production-inhibiting gas from the external gas to the heating unit.

[0159] The heat-treated product that has undergone heat treatment in the heating unit 3 is cooled in the cooling unit 4 of the heat treatment furnace 2 shown in Figure 2 and discharged from the discharge port 7. It should be noted that the cooling of the heat-treated product can be performed after being discharged from the discharge port 7. The obtained sulfide-based solid electrolyte becomes a solid electrolyte with excellent battery performance by removing sulfur attached to the surface of the sulfide-based solid electrolyte material to make the crystal structure homogeneous.

[0160] (Manufacturing apparatus for sulfide-based solid electrolyte according to the second embodiment)

[0161] Refer to Figure 7 、 Figure 8 to describe the second embodiment of this manufacturing apparatus. In the second embodiment, this manufacturing apparatus has a rotary kiln furnace.

[0162] Figure 7 is a side cross-sectional schematic view showing an example of this manufacturing apparatus of the rotary kiln furnace type. Figure 8 is a side cross-sectional schematic view showing an example of the sliding portion of the rotating member and the pressurization chamber in this manufacturing apparatus of the rotary kiln furnace type.

[0163] Figure 7In [the device], the manufacturing device 21 of the rotary kiln furnace type includes a hearth tube 22 having a heating section 23 for heat-treating a sulfide-based solid electrolyte material. The hearth tube 22 is provided with a bearing 29b on the inlet 24 side and a bearing 29a on the outlet 26 side, and is arranged such that the bearing 29a side is lower than the bearing 29b side. The hearth tube 22 arranged in such a gradient manner is rotated by a rotation drive section 30, so that the sulfide-based solid electrolyte material is conveyed from the inlet 24 side through the heating section 23 to the outlet 26 side. That is, in the manufacturing device of the rotary kiln furnace type, the hearth tube 22 is a rotating component for feeding a sulfide-based solid electrolyte material into its interior and conveying it.

[0164] As Figure 7 shown, in the manufacturing device 21, the hearth tube 22 is arranged so as to penetrate the heating section 23, and the hearth tube 22 has a sliding section as a boundary section in the sealing section 35. Specifically, for example, as Figure 8 shown, there is a sliding section 33 as a boundary section between a sealing ring (rotating component side) 32 provided on the hearth tube 22 and a sealing ring (fixed component side) 31 provided on the inlet section 25, and the inlet section 25 is arranged so as to cover the end opening on the inlet 24 side of the hearth tube 22. The sealing ring can be provided on the hearth tube 22 or the inlet section 25 via a setting component for setting the sealing ring.

[0165] The manufacturing device 21 has a pressurizing chamber 28 for pressurizing the sliding section 33 from the outside of the hearth tube 22.

[0166] It should be noted that, as Figure 7 shown, similar to the inlet section 25 side, there is also a sliding section 33 (not shown) on the discharge section 27 side arranged to cover the end opening on the outlet 26 side of the hearth tube 22, and the pressurizing chamber 28 is provided to cover the sliding section 33.

[0167] The manufacturing method of the sulfide-based solid electrolyte when using the present manufacturing device 21 of the rotary kiln furnace type will be described below.

[0168] A sulfide-based solid electrolyte material is fed from the inlet 24. Since the hearth tube 22 is arranged in a gradient manner, the sulfide-based solid electrolyte material is conveyed to the heating section 23. It is preferable to replace the atmosphere in the passage area of the sulfide-based solid electrolyte material from the inlet 24 to the outlet 26 with an inert gas in advance, and when feeding the sulfide-based solid electrolyte material, the purge section (not shown) near the inlet 24 is filled with an inert gas or the like and then the sulfide-based solid electrolyte material is fed.

[0169] The sulfide-based solid electrolyte material transported to the heating unit 23 is heat-treated. The preferred conditions for the heat treatment are as described above. At this time, the heat treatment is performed while controlling the pressure in the pressurization chamber 28 to be higher than the pressure in the heating unit 23 and the external air pressure. The preferred conditions for pressurization are as described above.

[0170] As Figure 8 shown, pressurization of the pressurization chamber can be performed by supplying pressurized gas from the pressurized gas supply port 34 provided in the pressurization chamber 28. For example, gas is supplied from a gas supply unit (not shown) to the pressurized gas supply port 34 through a pipe (not shown).

[0171] Preferably, an oxygen supply unit (not shown) for supplying oxygen is provided to supply a gas containing oxygen to the pressurization chamber 28. The gas containing oxygen is, for example, a mixed gas formed by mixing oxygen supplied from the oxygen supply unit and an inert gas supplied from an inert gas supply unit (not shown) in a pipe connecting each supply unit and the pressurized gas supply port 34, and is supplied to the pressurization chamber 28 from the pressurized gas supply port 34. Additionally, for example, oxygen supplied from the oxygen supply unit and an inert gas supplied from the inert gas supply unit can be supplied separately from a plurality of pressurized gas supply ports 34.

[0172] If the sulfide-based solid electrolyte material is heat-treated in the heating unit 23, sulfur attached to the surface of the sulfide-based solid electrolyte material vaporizes. The vaporized sulfur is cooled on the furnace wall at the end of the furnace core tube 22 where the temperature is lower than that of the heating unit 23, on the wall of the charging unit 25 provided so as to cover the end opening of the furnace core tube 22, on the wall of the discharge unit 27, and on the sliding unit 33, and thus sulfur adheres to these parts. In this manufacturing method, by pressurizing the pressurization chamber 28, the gas supplied to the pressurization chamber leaks to the sliding unit 33, so that sulfur adhesion to the sliding unit 33 can be suppressed or the inflow of production-hindering gas from the external gas to the heating unit can be suppressed.

[0173] The heat-treated product that has undergone heat treatment in the heating unit 23 passes through Figure 7 the discharge unit 27 shown in the figure provided so as to cover the end opening of the furnace core tube 22 and is discharged from the discharge port 26. The heat-treated product passing through the discharge unit 27 is cooled in a cooling unit (not shown) provided between the discharge unit 27 and the discharge port 26, or can be cooled after the heat-treated product is discharged from the discharge port 26. The obtained sulfide-based solid electrolyte becomes a solid electrolyte with excellent battery performance by removing sulfur attached to the surface of the sulfide-based solid electrolyte material to make the crystal structure homogeneous.

[0174] (Manufacturing apparatus for sulfide-based solid electrolyte according to the third embodiment)

[0175] Refer to Figure 9 、 Figure 10A third embodiment of the present manufacturing apparatus will be described. In the third embodiment, the present manufacturing apparatus includes a stirring drying furnace.

[0176] Figure 9 It is a side cross-sectional schematic view showing an example of the present manufacturing apparatus of the stirring drying furnace type. Figure 10 It is a side cross-sectional schematic view showing an example of the sliding portion of the rotating member and the pressurizing chamber in the present manufacturing apparatus of the stirring drying furnace type.

[0177] Figure 9 In [the figure], the manufacturing apparatus 41 of the stirring drying furnace type includes a drying furnace 42 and a screw conveying section. The drying furnace 42 has a heating section 43 for heat-treating the sulfide-based solid electrolyte material. The screw conveying section has a drive shaft 44 and conveying blades 45 as a conveying mechanism for the sulfide-based solid electrolyte material. The screw conveying section conveys the sulfide-based solid electrolyte material by rotating the drive shaft 44 having the conveying blades 45 around the drive shaft 44 using a drive motor 51.

[0178] As Figure 9 shown, in the manufacturing apparatus 41, the drive shaft 44 of the screw conveying section is provided so as to penetrate the heating section 43. That is, in the manufacturing apparatus 41 of the stirring drying furnace type, the drive shaft 44 of the screw conveying section is a rotating member provided so as to penetrate the heating section 43. The drive shaft 44 has a sliding portion as a boundary portion at the shaft seal portion 48. Specifically, for example, as Figure 10 shown, a sliding portion 49 is provided between a seal ring 54 (rotating member side) provided on the drive shaft 44 and a seal ring 53 (fixed member side) provided on the furnace wall 52 of the drying furnace 42. The seal ring can be provided on the drive shaft 44 or the furnace wall 52 via a setting member for setting the seal ring.

[0179] The manufacturing apparatus 41 is provided with a pressurizing chamber 50 so as to pressurize the sliding portion 49 from the outside of the drying furnace 42 and the drive shaft 44.

[0180] Hereinafter, a method for manufacturing a sulfide-based solid electrolyte when using the present manufacturing apparatus 41 of the stirring drying furnace type will be described.

[0181] The sulfide-based solid electrolyte material is introduced from the inlet 46. The sulfide-based solid electrolyte material is conveyed to the heating section 43 by the screw conveying section. It is preferable to previously replace the atmosphere inside the drying furnace 42 with an inert gas, and when introducing the sulfide-based solid electrolyte material, the purging section (not shown) provided near the inlet 46 is filled with an inert gas or the like and then the sulfide-based solid electrolyte material is introduced.

[0182] The sulfide-based solid electrolyte material transported to the heating unit 43 is heat-treated. The preferred conditions for the heat treatment are as described above. At this time, the heat treatment is performed while controlling the pressure in the pressurization chamber 50 to be higher than the pressure in the heating unit 43 and the external air pressure. The preferred conditions for pressurization are as described above.

[0183] As Figure 10 shown, pressurization of the pressurization chamber can be performed by supplying pressurized gas from the pressurized gas supply port 55 provided in the pressurization chamber 50. For example, gas is supplied from a gas supply unit (not shown) to the pressurized gas supply port 55 through a pipe (not shown).

[0184] Preferably, an oxygen supply unit (not shown) for supplying oxygen is provided to supply a gas containing oxygen to the pressurization chamber 50. The gas containing oxygen can be, for example, a mixed gas formed by mixing oxygen supplied from the oxygen supply unit and an inert gas supplied from an inert gas supply unit (not shown) in a pipe connecting each supply unit to the pressurized gas supply port 55, and is supplied to the pressurization chamber 50 from the pressurized gas supply port 55. Additionally, for example, oxygen supplied from the oxygen supply unit and an inert gas supplied from the inert gas supply unit can be supplied separately from a plurality of pressurized gas supply ports 55.

[0185] If the sulfide-based solid electrolyte material is heat-treated in the heating unit 43, sulfur attached to the surface of the sulfide-based solid electrolyte material vaporizes. The vaporized sulfur is cooled on the furnace wall 52 or the sliding part 49 at the end of the drying furnace 42 where the temperature is lower than that of the heating unit 43, so sulfur adheres to these parts. In this manufacturing method, by pressurizing the pressurization chamber 50, the gas supplied to the pressurization chamber leaks to the sliding part 49, so that the adhesion of sulfur to the sliding part 49 can be suppressed or the inflow of production-hindering gas from the external gas to the heating unit can be suppressed.

[0186] The heat-treated product that has undergone heat treatment in the heating unit 43 is discharged from Figure 9 the discharge port 47 shown. The heat-treated product that has undergone heat treatment in the heating unit 43 can be cooled in a cooling unit (not shown) provided between the heating unit 43 and the discharge port 47, or can be cooled after discharging the heat-treated product from the discharge port 47. The obtained sulfide-based solid electrolyte is made to have a homogeneous crystal structure by removing sulfur attached to the surface of the sulfide-based solid electrolyte material, thereby becoming a solid electrolyte with excellent battery performance.

[0187] (Crushing)

[0188] The obtained sulfide-based solid electrolyte can be further crushed to be further micronized. As a method of crushing, for example, a wet crushing method can be cited. In the case of the wet crushing method, the type of solvent used is not particularly limited, and since the sulfide-based solid electrolyte has the property of being easily deteriorated by reacting with moisture, it is preferable to use a non-aqueous organic solvent.

[0189] The type of non-aqueous organic solvent is not particularly limited, and examples thereof include hydrocarbon solvents, organic solvents containing a hydroxyl group, organic solvents containing an ether group, organic solvents containing a carbonyl group, organic solvents containing an ester group, organic solvents containing an amino group, organic solvents containing a formyl group, organic solvents containing a carboxyl group, organic solvents containing an amide group, organic solvents containing a benzene ring, organic solvents containing a mercapto group, organic solvents containing a thioether group, organic solvents containing a thioester group, organic solvents containing a disulfide group, halogenated alkyls, etc.

[0190] As the hydrocarbon solvent, for example, cyclohexane, heptane, octane, and toluene can be cited. From the viewpoint of low saturated water concentration, cyclohexane, heptane, and octane are preferred. In addition, from the viewpoint of adjusting the water concentration, a mixed solvent obtained by mixing these hydrocarbon solvents with toluene or dibutyl ether is also preferred.

[0191] When pulverizing the sulfide-based solid electrolyte, from the viewpoint of preventing the reaction between the sulfide-based solid electrolyte and water and decreasing the lithium ion conductivity, the lower the water concentration of the above non-aqueous organic solvent, the better. The water concentration of the above non-aqueous organic solvent can be, for example, 170 mass ppm or less, 150 mass ppm or less, 120 mass ppm or less, 100 mass ppm or less.

[0192] The wet pulverization method can be carried out, for example, using a pulverizer such as a ball mill, a planetary ball mill, or a bead mill. In the wet pulverization, in addition to the above solvents, an ether compound, an ester compound, or a nitrile compound can be added as an additive (dispersant).

[0193] When a solvent or an additive remains in the sulfide-based solid electrolyte obtained by wet pulverization, a drying process can be carried out. As the drying conditions, for example, the temperature can be 100°C to 200°C. The drying time is not particularly limited and can be, for example, 10 minutes to 24 hours. In addition, the drying process can be carried out under reduced pressure, for example, the absolute pressure can be 50 kPa or less. The drying process can be carried out using a hot plate, a drying furnace, an electric furnace, etc.

[0194] (Sulfide-based solid electrolyte)

[0195] As the sulfide-based solid electrolyte obtained by this manufacturing method, a sulfide-based solid electrolyte containing a lithium element can be cited. As the sulfide-based solid electrolyte obtained by this manufacturing method, for example, sulfide-based solid electrolytes having an LGPS-type crystal structure such as Li 10 GeP2S 12 etc., Li6PS5Cl, Li 5.4 PS 4.4 Cl 1.6 and Li5.4 PS 4.4 Cl 0.8 Br 0.8 sulfide-based solid electrolytes having a argyrodite-type crystal structure, such as Li-P-S-Ha systems (Ha represents at least one element selected from halogen elements), glass ceramics of Li-P-S-Ha systems, and Li7P3S 11 and other LPS glass ceramics, etc.

[0196] The sulfide-based solid electrolyte can be a sulfide-based solid electrolyte having a specific crystal structure according to its purpose, or a sulfide-based solid electrolyte containing a crystalline phase and an amorphous phase. From the viewpoint of lithium ion conductivity, the crystalline phase is more preferably an argyrodite-type crystalline phase.

[0197] As the sulfide-based solid electrolyte having excellent lithium ion conductivity, a sulfide-based solid electrolyte having elements of Li-P-S-Ha is preferred, and a crystalline phase is more preferred. In addition, the halogen element is preferably derived from one or more selected from lithium chloride, lithium bromide, and lithium iodide.

[0198] From the viewpoint of good battery characteristics when used in a lithium ion secondary battery, the lithium ion conductivity of the sulfide-based solid electrolyte is preferably 1.0×10 -4 S / cm or more, more preferably 5.0×10 -4 S / cm or more, further preferably 1.0×10 - 3 S / cm or more, particularly preferably 5.0×10 -3 S / cm or more. The above lithium ion conductivity is measured by using an alternating current impedance tester (for example, manufactured by Bio-Logic Sciences Instruments, potentiostat / galvanostat VSP), with the measurement conditions being measurement frequency: 100 Hz to 1 MHz, measurement voltage: 100 mV, and measurement temperature: 25°C.

[0199] The obtained sulfide-based solid electrolyte can be identified by analyzing the crystal structure through X-ray diffraction (XRD) measurement or by analyzing the elemental composition using various methods such as ICP emission spectrometry, atomic absorption spectrometry, and ion chromatography. For example, P and S can be measured by ICP emission spectrometry, Li can be measured by atomic absorption spectrometry, and Ha can be measured by ion chromatography.

[0200] In addition, by performing Raman spectroscopy, it is possible to evaluate the homogeneity of the composition of the sulfide-based solid electrolyte. Specifically, for a sample obtained from the resulting sulfide-based solid electrolyte, Raman spectroscopy is performed at two or more arbitrary points. It should be noted that, from the viewpoint of improving the accuracy of the evaluation, the number of measurement points is preferably 8 or more, and more preferably 10 or more. As the preferred conditions for Raman spectroscopy when evaluating the homogeneity of the composition of the sulfide-based solid electrolyte, for example, a spot diameter of 3 μm and a number of measurement points of 10 can be cited. By setting the spot diameter to 3 μm, the analysis region in Raman spectroscopy becomes a size suitable for evaluating the homogeneity of the composition of the sulfide-based solid electrolyte at the microscopic level.

[0201] It is considered that the smaller the deviation of the peak wavenumber (peak position) of PS4 3- etc. from the structure of the sulfide-based solid electrolyte in each measurement result, the more homogeneous the composition of the sulfide-based solid electrolyte. Or it is considered that the smaller the deviation of the full width at half maximum of the peak from the structure of the sulfide-based solid electrolyte, the more homogeneous the composition of the sulfide-based solid electrolyte.

[0202] Although it varies depending on the composition of the resulting sulfide-based solid electrolyte, it is preferable to identify the peak from the P-S bond as the peak from the structure of the sulfide-based solid electrolyte. The position of the peak from the P-S bond varies depending on the composition system and is typically included between 350 cm -1 ~500 cm -1 Hereinafter, in this specification, the deviation of the peak position or the deviation of the full width at half maximum of the peak refers to the value obtained by identifying the peak with the strongest intensity among the peaks from the P-S bond.

[0203] The deviation of the peak position can be evaluated as follows. That is, when calculating the standard deviation of the peak positions of each measurement point obtained by Raman spectroscopy and recording it as (peak position average) ± (standard deviation), the value of the standard deviation is preferably within 2 cm -1 or less, more preferably within 1 cm -1 or less, and further preferably within 0.5 cm -1 or less. It should be noted that here, the peak position refers to the position of the peak apex. For example, for the sulfide-based solid electrolyte obtained by this manufacturing method, when performing Raman spectroscopy with a spot diameter of 3 μm and a number of measurement points of 10, the standard deviation of the peak positions of the peaks from the P-S bond in the range of 350 cm -1 ~500 cm -1 is preferably within 2 cm -1 or less, more preferably within 1 cm -1 or less, and further preferably within 0.5 cm -1 or less.

[0204] The deviation of the full width at half maximum (FWHM) of the peak can be evaluated as follows. That is, the standard deviation of the FWHM of the peak at each measurement point obtained by Raman spectroscopy measurement is calculated by finding the FWHM of each peak and then finding the standard deviation of this value. When it is recorded as (average FWHM of the peak) ± (standard deviation), the value of the standard deviation is preferably 2 cm -1 or less, more preferably 1.5 cm -1 or less. It should be noted that here, the FWHM of the peak refers to the width at the intersection of the peak intensity value half of the peak from the above-mentioned P-S bond and the peak from the P-S bond when the Raman spectrum is plotted. For example, for the sulfide-based solid electrolyte obtained by this manufacturing method, when the spot diameter is 3 μm and the number of measurement points is 10 for Raman spectroscopy measurement, the standard deviation of the FWHM of the peak from the P-S bond at 350 cm -1 to 500 cm -1 is preferably 2 cm -1 or less, more preferably 1.5 cm -1 or less.

[0205] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and can be appropriately modified and improved, etc. In addition, the materials, shapes, sizes, numbers, and arrangement positions of the respective constituent elements in the above-described embodiments are arbitrary as long as the present invention can be implemented, and are not limited.

[0206] As described above, the following matters are disclosed in this specification.

[0207] [1] A method for manufacturing a sulfide-based solid electrolyte, which is a method for manufacturing a sulfide-based solid electrolyte by supplying a sulfide-based solid electrolyte material to a heat treatment device for heat treatment,

[0208] The above heat treatment device includes: a heating unit for heat-treating the sulfide-based solid electrolyte material; a rotating member for conveying while heating the sulfide-based solid electrolyte material through the heating unit; a fixing member disposed on the end side in the axial direction of the rotating member and having a fixed position; and a pressurizing chamber for pressurizing the boundary portion between the rotating member and the fixing member,

[0209] while controlling the pressure in the pressurizing chamber to a pressure higher than the pressure in the heating unit and the external air pressure, heat-treat the sulfide-based solid electrolyte material.

[0210] [2] The method for manufacturing a sulfide-based solid electrolyte according to the above [1], wherein the sulfide-based solid electrolyte material is obtained by mechanically grinding or heating and melting a sulfide-based solid electrolyte raw material.

[0211] [3] The manufacturing method of the sulfide-based solid electrolyte according to [1] or [2] above, wherein the oxygen concentration in the pressurization chamber is 10 volume ppm or more.

[0212] [4] The manufacturing method of the sulfide-based solid electrolyte according to any one of [1] to [3] above, wherein the heating temperature of the heating unit is 300 °C or more.

[0213] [5] The manufacturing method of the sulfide-based solid electrolyte according to any one of [1] to [4] above, wherein the pressure differences between the pressure in the pressurization chamber, the pressure in the heating unit, and the external air pressure are each 0.1 kPa or more.

[0214] [6] The manufacturing method of the sulfide-based solid electrolyte according to any one of [1] to [5] above, wherein the sulfide-based solid electrolyte material is continuously supplied for heat treatment.

[0215] [7] A manufacturing apparatus for a sulfide-based solid electrolyte, comprising:

[0216] A heating unit that performs heat treatment on a sulfide-based solid electrolyte material;

[0217] A rotating member that conveys while heating the sulfide-based solid electrolyte material through the heating unit;

[0218] A fixing member disposed on the end side in the axial direction of the rotating member and having a fixed position; and

[0219] A pressurization chamber that pressurizes the boundary portion between the rotating member and the fixing member

[0220] [8] The manufacturing apparatus for a sulfide-based solid electrolyte according to [7] above, further comprising an oxygen supply unit that supplies oxygen to the pressurization chamber.

[0221] Examples

[0222] Examples are given below to specifically illustrate the present invention, but the present invention is not limited to these. Examples 1 to 3 are examples, and Example 4 is a comparative example.

[0223] Example 1

[0224] According to Figure 2 the specifications of the manufacturing apparatus 1 shown, tests were conducted.

[0225] The sulfide-based solid electrolyte material is obtained as follows. That is, the raw materials are mixed in such a way that the molar ratio of Li2S, P2S5, LiCl, and LiBr is (1.9:0.5:1.0:0.6), and 500 g of the mixed raw materials are prepared. In a glove box under a nitrogen atmosphere, the mixed raw materials and zirconia balls with a diameter of φ10 mm are added to a zirconia pot and completely sealed. Mechanical milling treatment is carried out for 15 hours at a rotation speed of 370 rpm using a planetary ball mill to obtain the sulfide-based solid electrolyte material.

[0226] Nitrogen purging is carried out with the pressure of the heating part 3 in the heat treatment furnace 2 being 0.05 kPa, the dew point being -60 °C, and the oxygen concentration being less than 50 volume ppm.

[0227] A pressurized gas, which is a mixed gas of oxygen and nitrogen, is supplied in such a way that the heating temperature of the heating part 3 is 430 °C, the pressure in the pressurizing chamber is 0.55 kPa, the dew point is less than 0 °C, and the oxygen concentration is 100 volume ppm. That is, the difference between the pressure in the pressurizing chamber and the pressure in the heating part is 0.5 kPa, and the difference between the pressure in the pressurizing chamber and the external air pressure is 0.55 kPa.

[0228] Next, 500 g of the above sulfide-based solid electrolyte material is added to the conveying container, and while nitrogen purging is carried out on the purging part provided near the inlet 6, it is put into the heat treatment furnace 2 and conveyed to the heating part 3 by the conveying roller 5 for heat treatment.

[0229] The heat-treated product is cooled in the cooling part 4, and the sulfide-based solid electrolyte is taken out.

[0230] The supply of the sulfide-based solid electrolyte material to the heating part 3 is continuously supplied to the container at a conveying speed of 11 mm / minute, and heat treatment is continuously carried out for 1.5 hours. After 12 hours, the supply of the sulfide-based solid electrolyte material is stopped, and the operation of the manufacturing device 1 is stopped.

[0231] No solid attachment of sulfur was confirmed at the boundary part 9.

[0232] Example 2

[0233] According to Figure 7 the specifications of the manufacturing device 21 shown, tests are carried out.

[0234] The sulfide-based solid electrolyte material is the sulfide-based solid electrolyte material prepared in the same way as in Example 1.

[0235] Nitrogen purging is carried out with the pressure of the heating part 23 in the furnace core tube 22 being 0.05 kPa, the dew point being -60 °C, and the oxygen concentration being less than 50 volume ppm.

[0236] The pressurized gas is supplied in such a way that the heating temperature of the heating unit 23 is 430 °C, the pressure in the pressurizing chamber is 0.55 kPa, the dew point is less than 0 °C, and the oxygen concentration is 100 volume ppm. That is, the difference between the pressure in the pressurizing chamber and the pressure in the heating unit is 0.5 kPa, and the difference between the pressure in the pressurizing chamber and the external air pressure is 0.55 kPa.

[0237] Next, while nitrogen purging the purging unit provided near the inlet 24, the above-mentioned sulfide-based solid electrolyte material is continuously introduced from the inlet 24, transported to the heating unit 23, and heat-treated.

[0238] The heat-treated product is cooled, and the sulfide-based solid electrolyte is taken out.

[0239] The supply of the sulfide-based solid electrolyte material to the heating unit 23 is continuously supplied at a rate of 1 g / second. After 12 hours, when 43 kg of the sulfide-based solid electrolyte is obtained, the supply of the sulfide-based solid electrolyte material is stopped, and the operation of the manufacturing apparatus 21 is stopped.

[0240] No sulfur adhesion was confirmed at the sliding part 33.

[0241] Example 3

[0242] According to Figure 9 the specifications of the manufacturing apparatus 41 shown, tests are carried out.

[0243] The sulfide-based solid electrolyte material is the sulfide-based solid electrolyte material prepared in the same manner as in Example 1.

[0244] Nitrogen purging is carried out in such a way that the pressure of the heating unit 43 in the drying furnace 42 is 0.05 kPa, the dew point is -60 °C, and the oxygen concentration is less than 50 volume ppm.

[0245] The pressurized gas is supplied in such a way that the heating temperature of the heating unit 43 is 300 °C, the pressure in the pressurizing chamber is 0.55 kPa, the dew point is less than 0 °C, and the oxygen concentration is 100 volume ppm. That is, the difference between the pressure in the pressurizing chamber and the pressure in the heating unit is 0.5 kPa, and the difference between the pressure in the pressurizing chamber and the external air pressure is 0.55 kPa.

[0246] Next, while nitrogen purging the purging unit provided near the inlet 46, the above-mentioned sulfide-based solid electrolyte material is continuously introduced from the inlet 46, transported to the heating unit 43 by the screw conveyor, and heat-treated.

[0247] The heat-treated product is cooled, and the sulfide-based solid electrolyte is taken out.

[0248] The supply of the sulfide-based solid electrolyte material to the heating unit 43 is continuously supplied at a rate of 1 g / second. After 12 hours, the supply of the sulfide-based solid electrolyte material is stopped at the moment when 43 kg of the sulfide-based solid electrolyte is obtained, and the operation of the manufacturing apparatus 41 is stopped.

[0249] No sulfur adhesion was confirmed at the sliding part 49.

[0250] Example 4

[0251] Except that the pressurization chamber 10 is not provided, the test is conducted according to the specifications of the manufacturing apparatus 1 Figure 2 shown.

[0252] That is, all conditions except that the pressurization chamber 10 is not pressurized are the same as those in Example 1.

[0253] The operation of the manufacturing apparatus is stopped at the moment when 43 kg of the sulfide-based solid electrolyte is obtained.

[0254] Sulfur adhesion was confirmed at the boundary part 9.

[0255] The various embodiments have been described above with reference to the drawings, but the present invention is of course not limited to these examples. Those skilled in the art can clearly conceive of various modification examples or correction examples within the scope described in the claims for patent protection, and understanding these also naturally belongs to the technical scope of the present invention. In addition, within the scope not departing from the gist of the present invention, the constituent elements in the above-described embodiments can be arbitrarily combined.

[0256] It should be noted that this application is based on the Japanese Patent Application (Japanese Patent Application No. 2022-187379) filed on November 24, 2022, the content of which is incorporated herein by reference.

[0257] Symbol Explanation

[0258] 1, 21, 41 Manufacturing apparatus for sulfide-based solid electrolyte

[0259] 2 Heat treatment furnace

[0260] 3 Heating unit

[0261] 4 Cooling unit

[0262] 5 Conveyor roller

[0263] 6 Inlet

[0264] 7 Outlet

[0265] 8 Furnace wall

[0266] 9 Boundary part

[0267] 10 Pressurization chamber

[0268] Roll bearings 11a and 11b

[0269] Drive motor 12

[0270] Pressurized gas supply port 13

[0271] Hearth tube 22

[0272] Heating section 23

[0273] Feed inlet 24

[0274] Feeding section 25

[0275] Discharge port 26

[0276] Discharge section 27

[0277] Pressurizing chamber 28

[0278] Bearings 29a and 29b

[0279] Rotary drive section 30

[0280] Sealing ring (fixed part side) 31

[0281] Sealing ring (rotating part side) 32

[0282] Sliding section 33

[0283] Pressurized gas supply port 34

[0284] Sealing section 35

[0285] Drying furnace 42

[0286] Heating section 43

[0287] Drive shaft 44

[0288] Conveyor blade 45

[0289] Feed inlet 46

[0290] Discharge port 47

[0291] Shaft seal section 48

[0292] Sliding section 49

[0293] Pressurizing chamber 50

[0294] Drive motor 51

[0295] Furnace wall 52

[0296] Sealing ring (fixed part side) 53

[0297] Sealing ring (rotating part side) 54

[0298] 55 Pressurized gas supply port

Claims

1. A method for manufacturing a sulfide-based solid electrolyte, which is a method for manufacturing a sulfide-based solid electrolyte by supplying a sulfide-based solid electrolyte material to a heat treatment device for heat treatment. The heat treatment device has: a heating unit that heat-treats the sulfide-based solid electrolyte material; a rotating member that conveys the sulfide-based solid electrolyte material while heating it through the heating unit; a fixed member that is disposed on the end side in the axial direction of the rotating member and is stationary; and a pressurization chamber that pressurizes the boundary portion between the rotating member and the fixed member. While controlling the pressure of the pressurization chamber to be higher than the pressure of the heating unit and the external air pressure, the sulfide-based solid electrolyte material is heat-treated.

2. The manufacturing method of the sulfide-based solid electrolyte according to claim 1, wherein, The sulfide-based solid electrolyte material is obtained by mechanically grinding or heating and melting a sulfide-based solid electrolyte raw material.

3. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, The oxygen concentration in the pressurization chamber is 10 volume ppm or more.

4. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, The heating temperature of the heating unit is 300 °C or more.

5. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, The pressure differences between the pressure of the pressurization chamber and the pressures of the heating unit and the external air pressure are each 0.1 kPa or more.

6. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, The sulfide-based solid electrolyte material is continuously supplied for heat treatment.

7. A manufacturing device for a sulfide-based solid electrolyte, comprising: a heating unit that heat-treats a sulfide-based solid electrolyte material; a rotating member that conveys the sulfide-based solid electrolyte material while heating it through the heating unit; a fixed member that is disposed on the end side in the axial direction of the rotating member and is stationary; and a pressurization chamber that pressurizes the boundary portion between the rotating member and the fixed member.

8. The manufacturing device for a sulfide-based solid electrolyte according to claim 7, wherein it further comprises an oxygen supply unit that supplies oxygen to the pressurization chamber.

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