Manufacturing method and manufacturing device for sulfide solid electrolyte powder

Abstract

The present invention pertains to a manufacturing method for a sulfide solid electrolyte powder, the method comprising: obtaining a melt by heating and melting a sulfide solid electrolyte feedstock in a furnace body; injecting a gas into the melt while discharging the melt from the furnace body, and cooling, solidifying, and pulverizing the melt, thereby obtaining a sulfide solid electrolyte powder; exhausting the injected gas; and removing a residue contained in the exhausted gas, wherein the residue contains at least a fine powder of sulfide solid electrolyte.

Description

Method and apparatus for producing sulfide solid electrolyte powder

[0001] This invention relates to a method and apparatus for producing sulfide solid electrolyte powder.

[0002] Lithium-ion rechargeable batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Traditionally, lithium-ion rechargeable batteries have used liquid electrolytes. However, in recent years, all-solid-state lithium-ion rechargeable batteries, which use solid electrolytes, have attracted attention due to the potential for improved safety, faster charging and discharging, and smaller case sizes.

[0003] Examples of solid electrolytes used in all-solid-state lithium-ion secondary batteries include sulfide solid electrolytes.

[0004] One method for synthesizing sulfide solid electrolytes involves heating and melting sulfide solid electrolyte raw materials to prepare a melt, which is then cooled and solidified. For example, Patent Document 1 discloses a method for producing solid electrolyte glass by melting and cooling compressed raw materials. Patent Document 2 describes a method for synthesizing an electron-lithium ion mixed conductor by mixing multiple sulfides and transition metal sulfides, heating and melting them, and then rapidly cooling the melt.

[0005] However, in the methods described in Patent Documents 1 and 2, the molten material comes into contact with various components when it cools and solidifies, which can lead to contamination by impurities, making it impossible to obtain a high-purity sulfide solid electrolyte powder with the desired composition. Furthermore, obtaining a powdered sulfide solid electrolyte requires a further grinding step after the cooling step, which complicates the manufacturing process and requires a lot of time.

[0006] Therefore, Patent Document 3 discloses a method for easily producing sulfide solid electrolyte powder with excellent battery performance while suppressing contamination by impurities due to contact with materials, by injecting gas into the melt while discharging the melt from the furnace body, thereby cooling and solidifying the melt and turning it into powder.

[0007] Japanese Patent No. 5640665, Japanese Patent No. 4399903, International Publication No. 2023 / 219067

[0008] When attempting to manufacture sulfide solid electrolyte powder by cooling, solidifying, and pulverizing it using gas injection, it is conceivable to pass the exhaust gas through a filter, for example. However, unlike when cooling, solidifying, and pulverizing molten materials such as steel using gas injection, it has been found that in the case of sulfide solid electrolyte powder, the filter through which the exhaust gas passes becomes clogged, causing pressure fluctuations. Pressure fluctuations can lead to abnormalities in the quality of the resulting sulfide solid electrolyte and make continuous production of sulfide solid electrolyte powder difficult.

[0009] Therefore, the present invention aims to provide a new manufacturing method for sulfide solid electrolyte powder, which involves cooling and solidifying a molten liquid by gas injection and then pulverizing it, and which is capable of continuous production. Furthermore, the present invention aims to provide a manufacturing apparatus that is capable of continuous production even when employing the above-described manufacturing method.

[0010] Through our investigations, we have concluded that the residue contained in the exhaust gas contains at least fine particles of sulfide solid electrolyte, and that these should be removed. In the first embodiment, it was found that the above residue further contains low-melting-point substances with a melting point of 300°C or less, and that the clogging of the filter is caused by the presence of low-melting-point substances such as sulfur in the exhaust gas. We then found that the above problem could be solved by employing an alkaline scrubber, and thus completed the present invention. In the second embodiment, it was found that the above residue further contains sulfur, and that the clogging of the filter is caused by the presence of sulfur with a low melting point in the exhaust gas. We then found that the above problem could be solved by contacting the sulfur with molten sulfur, and thus completed the present invention. In the third embodiment, it was found that the above residue further contains low-melting-point substances with a melting point of 300°C or less, and that the clogging of the filter is caused by low-melting-point substances with a melting point of 300°C or less contained in the exhaust gas. Specifically, because of its low melting point, the low-melting-point substance exists in the exhaust gas as a mist, which adheres to the filter as a sticky substance, causing the filter to become clogged. In response to this, the inventors conducted further research and found that the above problem could be solved by cooling the mist-like low-melting-point substance to turn it into dust before capturing it with a filter, thus completing the present invention.

[0011] In other words, the gist of the present invention is as follows.

[0012] [1] A method for producing sulfide solid electrolyte powder, comprising: heating and melting a sulfide solid electrolyte raw material in a furnace to obtain a melt; injecting gas into the melt while discharging the melt from the furnace to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; exhausting the gas after injection; and removing the residue contained in the exhausted gas, wherein the residue contains at least fine powder of sulfide solid electrolyte. [2] The method for producing sulfide solid electrolyte powder according to [1], wherein the residue further contains a low melting point substance having a melting point of 300°C or less, and the removal of the residue is performed by an alkaline scrubber. [3] The method for producing sulfide solid electrolyte powder according to [1], wherein the residue further contains sulfur, and the removal of the residue is performed by contacting the exhausted gas with molten sulfur. [4] The method for producing sulfide solid electrolyte powder according to [1], wherein the residue further contains a low-melting-point substance having a melting point of 300°C or less, the residue is removed by a filter, and the mist-like low-melting-point substance contained in the residue is cooled to become dust and then captured by the filter.

[0013] [5] The method for producing sulfide solid electrolyte powder according to [2], wherein the low-melting-point substance is at least one selected from sulfur, iodine, bromine, chlorine, hydrogen halide, and phosphorus pentasulfide. [6] The method for producing sulfide solid electrolyte powder according to [2] or [5], further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection. [7] The method for producing sulfide solid electrolyte powder according to [6], wherein the separation is performed by centrifugal force. [8] The method for producing sulfide solid electrolyte powder according to any one of [2], [5] to [7], wherein the exhaust linear velocity during exhaust is 10 m / s or more. [9] The method for producing sulfide solid electrolyte powder according to any one of [2], [5] to [8], wherein the pH of the alkaline solution inside the alkali scrubber is 11 or more.

[0014]

[10] The method for producing sulfide solid electrolyte powder according to [3], further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection.

[11] The method for producing sulfide solid electrolyte powder according to

[10] , wherein the separation is performed by centrifugal force.

[0015]

[12] The method for producing sulfide solid electrolyte powder according to [4], wherein the low melting point substance is at least one selected from sulfur, iodine, and phosphorus pentasulfide.

[13] The method for producing sulfide solid electrolyte powder according to [4] or

[12] , further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection.

[14] The method for producing sulfide solid electrolyte powder according to

[13] , wherein the separation is performed by centrifugal force.

[15] The method for producing sulfide solid electrolyte powder according to any one of [4],

[12] to

[14] , wherein the filter is a bag filter.

[0016] Here, focusing on [2] above as the first embodiment, the gist of the first embodiment is as follows: [1A] A method for producing sulfide solid electrolyte powder, comprising: heating and melting a sulfide solid electrolyte raw material in a furnace to obtain a melt; injecting gas into the melt while discharging the melt from the furnace to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; exhausting the gas after injection; and removing the residue contained in the exhausted gas, wherein the residue comprises fine powder of sulfide solid electrolyte and a low-melting-point substance with a melting point of 300°C or less, and the removal of the residue is performed by an alkaline scrubber. [2A] The method for producing sulfide solid electrolyte powder according to [1A] above, wherein the low-melting-point substance is at least one selected from sulfur, iodine, bromine, chlorine, hydrogen halide, and phosphorus pentasulfide. [3A] A method for producing sulfide solid electrolyte powder according to [1A] or [2A], further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection. [4A] A method for producing sulfide solid electrolyte powder according to [3A], wherein the separation is performed by centrifugal force. [5A] A method for producing sulfide solid electrolyte powder according to any one of [1A] to [4A], wherein the exhaust linear velocity during exhaust is 10 m / s or more. [6A] A method for producing sulfide solid electrolyte powder according to any one of [1A] to [5A], wherein the pH of the alkaline solution inside the alkali scrubber is 11 or more.

[0017] [7A] A apparatus for producing sulfide solid electrolyte powder, comprising: a furnace body for heating and melting a sulfide solid electrolyte raw material to obtain a melt; a chamber for injecting gas into the melt discharged from the furnace body to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for recovering the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and an alkali scrubber, wherein the exhaust pipe is connected to the alkali scrubber. [8A] The apparatus for producing sulfide solid electrolyte powder according to [7A], further comprising a separation unit and a second vessel between the chamber and the exhaust pipe, wherein the separation unit separates the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, and the residue includes fine sulfide solid electrolyte powder and a low melting point substance with a melting point of 300°C or less. [9A] The apparatus for producing sulfide solid electrolyte powder according to [8A], wherein the low-melting-point substance is at least one selected from sulfur, iodine, bromine, chlorine, hydrogen halide, and phosphorus pentasulfide. [10A] The apparatus for producing sulfide solid electrolyte powder according to [8A] or [9A], wherein the separation unit is a centrifugal dust collection means. [11A] The apparatus for producing sulfide solid electrolyte powder according to any one of [7A] to [10A], wherein the pH of the alkaline solution inside the alkali scrubber is 11 or higher.

[12] The apparatus for producing sulfide solid electrolyte powder according to any one of [7A] to [11A], wherein the alkali scrubber contains packing material.

[0018] Here, focusing on [3] above as the second embodiment, the gist of the second embodiment is as follows: [1B] A method for producing sulfide solid electrolyte powder, comprising: heating and melting a sulfide solid electrolyte raw material in a furnace to obtain a melt; injecting gas into the melt while discharging the melt from the furnace to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; exhausting the gas after injection; and removing the residue contained in the exhausted gas, wherein the residue contains fine powder of sulfide solid electrolyte and sulfur, and the removal of the residue is performed by contacting the exhausted gas with molten sulfur. [2B] The method for producing sulfide solid electrolyte powder according to [1B], further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection. [3B] The method for producing sulfide solid electrolyte powder according to [2B], wherein the separation is performed by centrifugal force.

[0019] [4B] A apparatus for producing sulfide solid electrolyte powder, comprising: a furnace body that heats and melts a sulfide solid electrolyte raw material to obtain a melt; a chamber that injects gas into the melt discharged from the furnace body to cool, solidify and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for collecting the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and a trap containing molten sulfur, wherein the exhaust pipe and the trap are connected, and in the trap, the exhausted gas that has passed through the exhaust pipe comes into contact with the molten sulfur, and the residue contained in the exhausted gas is captured in the trap. [5B] The apparatus for producing sulfide solid electrolyte powder according to [4B], further comprising a separation unit and a second vessel between the chamber and the exhaust pipe, wherein the separation unit separates the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection. [6B] The apparatus for producing sulfide solid electrolyte powder according to [5B], wherein the separation unit is a centrifugal dust collection means. [7B] The apparatus for producing sulfide solid electrolyte powder according to any one of [4B] to [6B], wherein the trap is connected to a tank for removing the molten sulfur that has overflowed due to the capture of the residue.

[0020] Here, focusing on [4] above as the third form, the gist of the third form is as follows: [1C] A method for producing sulfide solid electrolyte powder, comprising: heating and melting a sulfide solid electrolyte raw material in a furnace to obtain a melt; injecting gas into the melt while discharging the melt from the furnace to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; exhausting the gas after injection; and removing the residue contained in the exhausted gas, wherein the residue contains fine powder of sulfide solid electrolyte and a low-melting-point substance with a melting point of 300°C or less; the removal of the residue is performed by a filter; and the mist-like low-melting-point substance contained in the residue is cooled to a dust-like state and then captured by the filter. [2C] The method for producing sulfide solid electrolyte powder according to [1C] above, wherein the low-melting-point substance is at least one selected from sulfur, iodine, and phosphorus pentasulfide. [3C] A method for producing sulfide solid electrolyte powder according to [1C] or [2C], further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection. [4C] A method for producing sulfide solid electrolyte powder according to [3C], wherein the separation is performed by centrifugal force. [5C] A method for producing sulfide solid electrolyte powder according to any one of [1C] to [4C], wherein the filter is a bag filter.

[0021] [6C] A apparatus for producing sulfide solid electrolyte powder, comprising: a furnace body that heats and melts a sulfide solid electrolyte raw material to obtain a melt; a chamber that injects gas into the melt discharged from the furnace body to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for collecting the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and a filter for removing residue contained in the exhausted gas, wherein the exhaust pipe and the filter are connected, the exhaust pipe is equipped with a cooling device, the residue contains fine powder of sulfide solid electrolyte and a low-melting-point substance with a melting point of 300°C or less, and as the exhaust pipe is cooled, the low-melting-point substance that has passed through the exhaust pipe changes from a mist to a dust and is captured by the filter. [7C] The apparatus for producing sulfide solid electrolyte powder according to [6C], wherein the low-melting-point substance is at least one selected from sulfur, iodine, and diphosphorus pentasulfide. [8C] The apparatus for producing sulfide solid electrolyte powder according to [6C] or [7C], further comprising a separation unit and a second vessel between the chamber and the exhaust piping, wherein the separation unit separates the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection. [9C] The apparatus for producing sulfide solid electrolyte powder according to [8C], wherein the separation unit is a centrifugal dust collection means. [10C] The apparatus for producing sulfide solid electrolyte powder according to any one of [6C] to [9C], wherein the cooling device is a spiral heat exchanger. [11C] The apparatus for producing sulfide solid electrolyte powder according to any one of [6C] to [10C], wherein the filter is a bag filter.

[0022] According to the present invention, continuous production becomes possible in a method for producing sulfide solid electrolyte powder by cooling and solidifying a molten liquid by gas injection and then pulverizing it.

[0023] Figure 1 is a flow diagram showing a first embodiment as one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 2 is a flow diagram showing a second embodiment as one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 3 is a flow diagram showing a third embodiment as one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 4 is a schematic diagram showing one aspect of a step in the first aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 5 is a schematic diagram showing one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 6 is a schematic diagram showing one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 7 is a schematic diagram showing one aspect of the alkali scrubber in the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 8 is a schematic diagram showing one aspect of the alkali scrubber in the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 9 is a schematic diagram showing one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 10 is a schematic diagram showing one aspect of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 11 is a schematic diagram showing one embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 12 is a schematic diagram showing one embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 13 is a schematic diagram showing one embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment. Figure 14 is a schematic diagram showing one embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment.

[0024] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower limit and upper limit. In this specification, mass% and weight%, and mass ratio and weight ratio are synonymous.

[0025] 《Method for producing sulfide solid electrolyte powder》 The method for producing sulfide solid electrolyte powder according to this embodiment comprises the following steps in order: Step 1: A step of heating and melting sulfide solid electrolyte raw material in a furnace to obtain a melt. Step 2: A step of injecting gas into the melt while discharging the melt from the furnace to cool, solidify and powderize the melt to obtain sulfide solid electrolyte powder. Step 3: A step of exhausting the gas after injection. Step 4: A step of removing the residue contained in the exhausted gas. Here, the gas exhausted in step 3 contains residue, and this residue contains at least fine powder of sulfide solid electrolyte.

[0026] In contrast to the above, in the first embodiment of this model, the residue contained in the gas exhausted in step 3 further includes a low-melting-point substance with a melting point of 300°C or less, in addition to the fine powder of the sulfide solid electrolyte, and it is preferable that the removal of the above residue in step 4 is carried out by an alkaline scrubber.

[0027] In contrast to the above, in the second embodiment of this model, the residue contained in the gas exhausted in step 3 further contains sulfur in addition to the fine powder of the sulfide solid electrolyte, and it is preferable that the removal of the above residue in step 4 is carried out by bringing the exhausted gas into contact with molten sulfur.

[0028] In contrast to the above, in the third embodiment of this model, the residue contained in the gas exhausted in step 3 further contains a low-melting-point substance with a melting point of 300°C or less, in addition to the fine powder of the sulfide solid electrolyte, and it is preferable that the removal of the above residue in step 4 is carried out by a filter. In this case, the mist-like low-melting-point substance contained in the residue is cooled to become dust before the residue is captured by the filter. The fine powder of the sulfide solid electrolyte is also captured by the filter, but since the fine powder of the sulfide solid electrolyte is already contained in the exhausted gas as fine powder (solid), it does not cause blockage of the filter, unlike the mist-like low-melting-point substance.

[0029] The first embodiment of the manufacturing method according to this embodiment will be explained using the flow chart in Figure 1. First, in step 1, the sulfide solid electrolyte raw material is heated and melted in a furnace to obtain a melt (step S1A). Next, in step 2, gas is injected into the melt while the melt is discharged from the furnace (step S2A). This cools and solidifies the melt and turns it into powder, obtaining sulfide solid electrolyte powder. Then, in step 3, the gas after injection is exhausted (step S3A). The exhausted gas contains not only the injected gas but also residues such as fine powder of the sulfide solid electrolyte and low-melting-point substances with a melting point of 300°C or less. Therefore, in step 4, the residues contained in the exhausted gas are removed by an alkali scrubber (step S4A), thereby separating the gas from the residues.

[0030] The second embodiment of the manufacturing method according to this embodiment will be explained using the flow chart in Figure 2. First, in step 1, the sulfide solid electrolyte raw material is heated and melted in a furnace to obtain a melt (step S1B). Next, in step 2, gas is injected into the melt while the melt is discharged from the furnace (step S2B). This cools and solidifies the melt and turns it into powder, obtaining sulfide solid electrolyte powder. Then, in step 3, the gas after injection is exhausted (step S3B), but the exhausted gas contains not only the injected gas but also residues such as fine powder of the sulfide solid electrolyte and sulfur. Therefore, in step 4, the exhausted gas is brought into contact with molten sulfur (step S4B), and the residue contained in the exhausted gas is removed, thereby separating the gas from the residue.

[0031] A third embodiment of the manufacturing method according to this embodiment will be explained using the flow chart in Figure 3. First, in step 1, the sulfide solid electrolyte raw material is heated and melted in a furnace to obtain a melt (step S1C). Next, in step 2, gas is injected into the melt while the melt is discharged from the furnace (step S2C). This cools and solidifies the melt and turns it into powder, obtaining sulfide solid electrolyte powder. Then, in step 3, the gas after injection is exhausted (step S3C). The exhausted gas contains not only the injected gas but also residues such as fine powder of the sulfide solid electrolyte and low-melting-point substances with a melting point of 300°C or less. Therefore, in step 4, in step S4C, the exhausted gas is cooled to turn the mist-like low-melting-point substances contained in the residue into dust (step S4C-1), and the residue is captured by a filter (step S4C-2). This separates the gas and residue without the filter becoming clogged.

[0032] The details of each process will be explained in order. Note that processes 1 and 2 are common to all three forms described above.

[0033] <Step 1> Step 1 is a process in which a sulfide solid electrolyte raw material is heated and melted inside the furnace to obtain a melt.

[0034] (Sulfide Solid Electrolyte Raw Materials) In this embodiment, various raw materials can be used as sulfide solid electrolyte raw materials depending on the desired composition of the sulfide solid electrolyte powder. In other words, the composition of the resulting sulfide solid electrolyte powder is not particularly limited.

[0035] In this embodiment, a commercially available sulfide solid electrolyte raw material may be used, or a sulfide solid electrolyte raw material manufactured from materials may be used. Furthermore, these sulfide solid electrolyte raw materials may be subjected to known pretreatments. In other words, the manufacturing method according to this embodiment may appropriately include a step of manufacturing a sulfide solid electrolyte raw material and a step of pretreating the sulfide solid electrolyte raw material.

[0036] The sulfide solid electrolyte raw material in this embodiment typically contains an alkali metal element (R) and a sulfur element (S).

[0037] Examples of the alkali metal element (R) include a lithium element (Li), a sodium element (Na), a potassium element (K), and the like. The alkali metal element (R) can be determined according to the secondary battery to which the sulfide solid electrolyte obtained by the manufacturing method according to the present embodiment is applied. For example, when used in a lithium ion battery, it is preferable to include a lithium element (Li) as the alkali metal element (R). When used in a sodium ion battery, it is preferable to include a sodium element (Na) as the alkali metal element (R). When used in a potassium ion battery, it is preferable to include a potassium element (K) as the alkali metal element (R).

[0038] As the alkali metal element (R), substances (components) containing an alkali metal element such as a simple alkali metal element or a compound containing an alkali metal element can be appropriately combined and used. For example, as the lithium element, substances (components) containing Li such as Li simple substance or a compound containing Li can be appropriately combined and used.

[0039] Examples of the substance containing a lithium element (Li) include, for example, lithium sulfide (Li ２ S), lithium iodide (LiI), lithium carbonate (Li ２ CO ３ ), lithium sulfate (Li ２ SO ４ ), lithium oxide (Li ２ O), lithium hydroxide (LiOH), and other lithium compounds, and metallic lithium and the like. From the viewpoint of obtaining a sulfide material, it is preferable to use lithium sulfide as the substance containing a lithium element (Li).

[0040] As the sulfur element (S), substances (components) containing S such as S simple substance or a compound containing S can be appropriately combined and used.

[0041] Examples of the substance containing a sulfur element (S) include, for example, phosphorus trisulfide (P ２ S ３ ), phosphorus pentasulfide (P ２ S ５ ), and other sulfur compounds containing phosphorus and elemental sulfur, compounds containing sulfur, and the like. Examples of the compound containing sulfur include H２ S, CS ２ , iron sulfide (FeS, Fe ２ S ３ FeS ２ Fe １－ｘ S, etc.), bismuth sulfide (Bi ２ S ３ ), copper sulfide (CuS, Cu ２ S, Cu １－ｘ Examples include sulfur (S), etc. From the viewpoint of obtaining sulfide materials, phosphorus sulfide is preferred among substances containing sulfur (S), and diphosphorus pentasulfide (P ２ S ５ ) is more preferable. These substances may be used individually or in combination of two or more. Note that phosphorus sulfide can be considered a compound that contains both S and P, as described later.

[0042] In this embodiment, the sulfide solid electrolyte raw material preferably further contains phosphorus (P) from the viewpoint of improving the ionic conductivity of the resulting sulfide solid electrolyte powder. As the phosphorus (P), substances (components) containing P, such as elemental P or compounds containing P, can be used in appropriate combinations.

[0043] Examples of substances containing phosphorus (P) include diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ ) such as phosphorus sulfide, sodium phosphate (Na ３ PO ４ Examples include phosphorus compounds such as ) and elemental phosphorus. As for substances containing the element of phosphorus (P), from the viewpoint of obtaining sulfide materials and from the viewpoint of exhibiting the effects of the present invention, highly volatile phosphorus sulfide is preferred, and diphosphorus pentasulfide (P ２ S ５ ) is more preferable. These substances may be used individually or in combination of two or more.

[0044] The sulfide solid electrolyte raw material in this embodiment may be obtained as a mixed raw material by appropriately mixing the above-mentioned substances according to the composition of the target sulfide solid electrolyte powder. The mixing ratio of each raw material when forming the mixed raw material is not particularly limited, but for example, the molar ratio S / R of sulfur element (S) to alkali metal element (R) in the sulfide solid electrolyte raw material is preferably 0.65 / 0.35 or less, and more preferably 0.5 / 0.5 or less, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte powder. Furthermore, it is preferable to obtain the mixed raw material by mixing in a predetermined stoichiometric ratio according to the substances used in the mixing. Examples of the above mixing methods include mixing in a mortar and pestle, mixing using media such as a planetary ball mill, media-less mixing such as a pin mill, powder stirrer, or airflow mixing.

[0045] As an example of a preferred combination of alkali metal elements and sulfur elements contained in the sulfide solid electrolyte raw material in this embodiment, Li ２ S and P ２ S ５ The following combinations can be cited. Li ２ S and P ２ S ５ When combining Li and P, the molar ratio Li / P is preferably 40 / 60 to 88 / 12, and more preferably 50 / 50 to 88 / 12. Here, the above molar ratio Li / P is preferably 40 / 60 or higher, more preferably 50 / 50 or higher, and preferably 88 / 12 or lower. ２ S ５ Li ２ By adjusting the above molar ratio so that it is relatively small relative to S, Li ２ P ２ S ５ The low boiling point makes it easier to suppress the volatilization of sulfur and phosphorus components during heat treatment.

[0046] On the other hand, since lithium sulfide is expensive, from the perspective of reducing the manufacturing cost of sulfide solid electrolyte powder, lithium compounds other than lithium sulfide, or metallic lithium, may be used. Specifically, the raw material for sulfide solid electrolyte can be a Li-containing substance such as metallic lithium, lithium iodide (LiI), or lithium carbonate (LiI). ２ CO３ ), lithium sulfate (Li ２ SO ４ ), lithium oxide (Li ２ Preferably, the substance contains one or more substances selected from the group consisting of 0) and lithium hydroxide (LiOH). These substances may be used individually or in combination of two or more.

[0047] The sulfide solid electrolyte raw material in this embodiment may contain additional substances (compounds, etc.) in addition to the above-mentioned substances, depending on the composition of the target sulfide solid electrolyte powder, or as an additive.

[0048] For example, when producing a sulfide solid electrolyte powder containing halogen elements such as F, Cl, Br, or I, it is preferable that the sulfide solid electrolyte raw material contains a halogen element (Ha). In this case, it is preferable that the sulfide solid electrolyte raw material contains a compound containing a halogen element. Examples of compounds containing halogen elements include lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), as well as phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, and boron halides. From the viewpoint of the reactivity of the raw material, lithium halides are preferred as the halogen element-containing compound, and LiCl, LiBr, and LiI are more preferred. These compounds may be used individually or in combination of two or more.

[0049] Furthermore, alkali metal halides such as lithium halides are also compounds containing alkali metal elements such as Li. When a sulfide solid electrolyte raw material contains alkali metal halides, some or all of the alkali metal elements such as Li in the sulfide solid electrolyte raw material may originate from alkali metal halides such as lithium halides.

[0050] In this embodiment, when the sulfide solid electrolyte raw material contains halogen elements (Ha) and phosphorus elements (P), the Ha content relative to P in the sulfide solid electrolyte raw material is preferably 0.2 to 4 molar equivalents. Here, from the viewpoint of improving the ionic conductivity of the obtained sulfide solid electrolyte powder, the above content is preferably 0.2 molar equivalents or more, and more preferably 0.5 molar equivalents or more. Furthermore, from the viewpoint of the stability of the obtained sulfide solid electrolyte powder, the above content is preferably 4 molar equivalents or less, and more preferably 3 molar equivalents or less.

[0051] Furthermore, as will be described later, when sulfur (S) and halogen (Ha) elements are included in the sulfide solid electrolyte raw material, oxidation resistance is required for the sulfur (S) element, while reduction resistance is required for the halogen (Ha) element when the melt is rapidly cooled in contact with a cooling member. Thus, the required properties of the two are different, and it has been difficult to select a corrosion-resistant member that can satisfy both. In contrast, in the manufacturing method according to this embodiment, the melt is cooled and solidified by injecting gas, so the above problem does not occur. Therefore, from the viewpoint of being able to better demonstrate the effects of the present invention, it is preferable that the sulfide solid electrolyte raw material in this embodiment includes both sulfur (S) and halogen (Ha) elements.

[0052] The resulting sulfide solid electrolyte powder may be amorphous, depending on the purpose. From the viewpoint of improving the ease of forming the amorphous phase, the sulfide solid electrolyte raw material may be SiS ２ , B ２ S ３ GeS ２ Al ２ S ３ It is also preferable to include sulfides such as the following. By making it easier to form an amorphous phase, when obtaining amorphous material by rapid cooling, amorphous sulfide solid electrolyte powder can be obtained even if the cooling rate is reduced, thereby reducing the load on the equipment.

[0053] From the viewpoint of imparting moisture resistance to sulfide solid electrolyte powders, the sulfide solid electrolyte raw material is SiO ２ , B ２ O ３ , GeO ２ Al ２ O ３ , P ２O ５ It is also preferable that these compounds contain oxides such as the following. These compounds may be used individually or in combination of two or more.

[0054] The above-mentioned sulfides and oxides may be included in the sulfide solid electrolyte raw material, or they may be added separately when the sulfide solid electrolyte raw material is heated and melted. Furthermore, the amount of sulfides and oxides added is preferably 0.1 to 50% by mass relative to the total amount of sulfide solid electrolyte raw material. Here, the amount added is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 50% by mass or less, and more preferably 40% by mass or less.

[0055] Furthermore, the sulfide solid electrolyte raw material in this embodiment may contain a compound that serves as a crystal nucleus, as described later.

[0056] As described above, the manufacturing method according to this embodiment can suppress the volatilization of the sulfide solid electrolyte raw material, and is therefore particularly suitable when the sulfide solid electrolyte raw material contains a highly volatile compound. Examples of highly volatile compounds include LiI and B. ２ S ３ S, Se, Sb ２ S ３ , and P ２ S ５ These are some examples.

[0057] (Heating and Melting) In this manufacturing method, as shown in Figure 4, first, the sulfide solid electrolyte raw material 12 introduced into the furnace body 10 is heated and melted to obtain a molten liquid 11. The furnace body 10 has a heating section (not shown) and is heated to a temperature at which the sulfide solid electrolyte raw material 12 melts.

[0058] When continuously supplying sulfide solid electrolyte raw material 12 into the furnace body 10, it is preferable to supply the sulfide solid electrolyte raw material 12 in a fixed quantity. The method of supplying in a fixed quantity is not particularly limited, but examples include using a screw feeder, a table feeder, or an airflow conveyor.

[0059] It is preferable to heat and melt the sulfide solid electrolyte raw material under a gas atmosphere containing sulfur. By heating and melting the sulfide solid electrolyte raw material under a gas atmosphere containing sulfur, sulfur is introduced into the melt. This suppresses the volatilization of sulfur during heating, thus allowing for appropriate control of the composition of the resulting sulfide solid electrolyte powder. Examples of gases containing sulfur include sulfur gas, hydrogen sulfide gas, carbon disulfide gas, and other compounds or gases containing sulfur.

[0060] A gas atmosphere containing sulfur elements may be obtained by supplying a sulfur source to a sulfide solid electrolyte raw material or melt and heating the sulfur source to generate a gas containing sulfur elements. By supplying a sulfur source to the sulfide solid electrolyte raw material, the sulfur source is also heated when the sulfide solid electrolyte raw material is heated and melted, so the sulfide solid electrolyte raw material can be heated and melted in a gas atmosphere containing the generated sulfur elements. Alternatively, by supplying a sulfur source to the melt, the sulfide solid electrolyte raw material can also be heated and melted in a gas atmosphere containing the generated sulfur elements.

[0061] The sulfur source is not particularly limited as long as it is elemental sulfur or a sulfur compound, but for example, elemental sulfur, hydrogen sulfide, organic sulfur compounds such as carbon disulfide, iron sulfide (FeS, Fe ２ S ３ FeS ２ Fe １－ｘ S, etc.), bismuth sulfide (Bi ２ S ３ ), copper sulfide (CuS, Cu ２ S, Cu １－ｘ Examples include polysulfides such as sodium polysulfide, lithium polysulfide, and sulfur-vulcanized rubber. A preferred sulfur source is sulfur powder.

[0062] Another method for creating a gaseous atmosphere containing sulfur elements is to introduce pre-obtained sulfur vapor into the furnace body. For example, sulfur is heated to 200-450°C to generate sulfur vapor, and N ２ By transporting inert gases such as gas, argon gas, and helium gas into the furnace as carrier gases, a gas atmosphere containing sulfur elements can be obtained.

[0063] The heating and melting temperature is not particularly limited, but is preferably 600 to 1000°C. Here, from the viewpoint of homogenizing the melt in a short time, the temperature is preferably 600°C or higher, more preferably 630°C or higher, and even more preferably 650°C or higher. Furthermore, from the viewpoint of suppressing deterioration and decomposition of components in the melt due to heating, the temperature is preferably 1000°C or lower, more preferably 950°C or lower, even more preferably less than 900°C, and particularly preferably less than 800°C.

[0064] When heating to the above temperature, the heating may be performed using a heating element provided in the furnace body. After that, it is sufficient to replenish the thermal energy lost during the heating and melting process. For example, the above temperature may be maintained by holding the internal temperature with a heater or the like.

[0065] The heating and melting time to obtain the melt can range from 0.5 to 100 hours. The above time is not particularly limited as long as the above-mentioned melt surface can be obtained, but it may be, for example, 0.5 hours or more, 1 hour or more, or 2 hours or more. Furthermore, the heating and melting time may be longer, as long as the deterioration or decomposition of the components in the melt due to heating is within an acceptable range. A practical range for the above time is preferably 100 hours or less, more preferably 50 hours or less, and even more preferably 25 hours or less.

[0066] The pressure during heating and melting is not particularly limited, but atmospheric pressure or slight pressure is preferred, and atmospheric pressure is more preferred.

[0067] During heating and melting, to prevent side reactions with water vapor, oxygen, etc., the dew point inside the furnace is preferably -20°C or lower. While there is no particular lower limit, it is usually -80°C or higher. The oxygen concentration is also preferably 1000 ppm by volume or lower.

[0068] <Step 2> Step 2 is a process in which the molten material obtained in Step 1 is discharged from the furnace body, and gas is injected into the molten material to cool, solidify, and pulverize it, thereby obtaining a sulfide solid electrolyte powder.

[0069] (Gas injection: Cooling, solidification, and pulverization) In the manufacturing method according to this embodiment, following the heating and melting in step 1 (steps S1A, S1B, and S1C), as shown in Figures 1 to 3, the molten sulfide solid electrolyte powder is cooled and solidified and pulverized by gas injection while discharging the molten sulfide solid electrolyte powder from the furnace body (steps S3A, S3B, and S3C), thereby obtaining sulfide solid electrolyte powder.

[0070] Specifically, as shown in Figure 4, the molten liquid 11 is discharged from the discharge section 13 provided in the furnace body 10 at any desired timing, and the process moves on to the cooling, solidification, and pulverization of the molten liquid 11.

[0071] In one embodiment of step 2 in this model, for example, the molten liquid 11 discharged from the discharge section 13 of the furnace body 10 is discharged into the chamber 15 through the molten liquid outlet section 14. Before the molten liquid 11 is discharged into the chamber 15 and falls, gas 17 is injected onto the discharged molten liquid 11 from a gas injection section 16 provided in the chamber 15. This cools and solidifies the molten liquid 11 and turns it into powder.

[0072] Thus, in the manufacturing method according to this embodiment, the molten material obtained in the furnace can be cooled, solidified, and pulverized by injecting gas into it. Because cooling and solidification are performed by gas injection, the process of converting the molten sulfide solid electrolyte raw material into sulfide solid electrolyte powder does not involve contact with components within the manufacturing apparatus, thereby suppressing contamination by impurities and obtaining sulfide solid electrolyte powder with excellent battery performance.

[0073] In particular, when manufacturing sulfide solid electrolyte powders containing sulfur (S) or halogen (Ha), it is generally preferable to rapidly cool the molten raw material to suppress the desorption and decomposition of electrolyte components and to achieve the desired crystal structure. However, if the molten material comes into contact with a component at a high temperature during rapid cooling, a reaction occurs at the interface. Furthermore, when rapidly cooling in contact with a component, oxidation resistance is required for sulfur (S), while reduction resistance is required for halogen (Ha). Since the required properties of these two are different, selecting a corrosion-resistant component that satisfies both has been difficult. For the reasons above, it is preferable to rapidly cool the molten material by a method that does not involve contact with the component, but rapid cooling of the molten material is difficult due to its large heat capacity. However, according to the manufacturing method of this embodiment, by employing gas injection, the material is powdered, and the gas-liquid and solid-gas interfaces become larger, making non-contact rapid cooling possible.

[0074] Furthermore, in the manufacturing method according to this embodiment, since no interfacial reaction occurs at the contact points between the components, the types of components used are not restricted, and the degree of freedom in selecting components is increased.

[0075] In addition to the above, since the molten material can be cooled and solidified simultaneously with pulverization by gas injection, there is no need for a separate pulverization process in addition to the cooling and solidification process. Furthermore, because gas injection and cooling can produce small-diameter powder, rapid cooling is possible. As a result, not only is the cooling time shortened and the production volume increased, but the quality is also improved due to the rapid cooling. In this way, gas injection makes it possible to produce sulfide solid electrolyte powder simply and with good quality without going through complex processes.

[0076] Methods for injecting gas include, for example, gas atomization.

[0077] It is preferable to use an inert gas such as nitrogen or argon as the above-mentioned gas.

[0078] The gas injection pressure is preferably 0.2 to 10 MPa. Here, from the viewpoint of reducing the powder particle size and lowering the heat capacity per unit of powder, the injection pressure is preferably 0.2 MPa or higher, more preferably 0.5 MPa or higher, and even more preferably 0.8 MPa or higher. Furthermore, from the viewpoint of continuous operation stability and realistic gas injection costs, the injection pressure is preferably 10 MPa or lower, more preferably 9.5 MPa or lower, and even more preferably 9 MPa or lower.

[0079] The gas velocity is not particularly limited, but may be, for example, 300 m / s or more, 350 m / s or more, or 400 m / s or more.

[0080] The oxygen concentration of the above gas may be adjusted as needed. The oxygen concentration of the above gas is preferably less than 100 ppm by volume, more preferably less than 10 ppm by volume, and even more preferably less than 1 ppm by volume. Furthermore, the dew point of the gas at atmospheric pressure is preferably less than -30°C, more preferably less than -40°C, and even more preferably less than -50°C.

[0081] It is preferable to perform the gas injection into the molten material within the chamber without exposing it to the atmosphere, and to recover the resulting sulfide solid electrolyte powder. This prevents the quality degradation of the sulfide solid electrolyte powder due to reactions with components in the atmosphere, particularly oxygen and moisture. Here, "chamber" refers to a chamber whose interior is isolated from the atmosphere, such as a vacuum chamber or a gas-sealed chamber.

[0082] The dew point inside the chamber is preferably below -30°C, more preferably below -40°C, and even more preferably below -50°C, from the viewpoint of maintaining the interface condition normally and preventing degradation of battery performance. The lower limit of the dew point inside the chamber is not particularly limited and can be within a practical range, but may be, for example, above -80°C.

[0083] From the viewpoint of maintaining the quality of the sulfide solid electrolyte powder and preventing degradation of battery performance, the oxygen concentration in the chamber is preferably less than 100 volume ppm, more preferably less than 10 volume ppm, and even more preferably less than 1 volume ppm. Furthermore, there is no particular lower limit to the oxygen concentration, but from the viewpoint of practical operating costs, it may be 0.01 volume ppm or higher.

[0084] In addition, when interrupting the cooling, solidification, and pulverization of the melt by gas injection, the gas 17 may be injected near the outlet on the chamber 15 side of the melt outflow portion 14 to cool and solidify the melt 11 discharged into the chamber 15, thereby sealing the outlet and stopping the outflow of the melt 11. When restarting the cooling, solidification, and pulverization of the melt by gas injection, the vicinity of the outlet may be heated with a heater or the like to release the seal near the outlet, thereby restarting the outflow of the melt 11.

[0085] The sulfide solid electrolyte powder obtained as described above may be reheated or pulverized as necessary. The reheating or pulverization may employ the methods of the conventional processes.

[0086] The obtained sulfide solid electrolyte powder exhibits the effects of the present invention by being subjected to the subsequent Step 3 and Step 4 regardless of its composition. Therefore, the composition of the sulfide solid electrolyte powder is not particularly limited. For example, sulfide solid electrolyte powders having an LGPS-type crystal structure such as Li １０ GeP ２ S １２ etc., sulfide solid electrolyte powders having an argyrodite-type crystal structure such as Li ６ PS ５ Cl, Li ５．４ PS ４．４ Cl １．６ Li ５．４ PS ４．４ Cl ０．８ Br ０．８ etc., crystallization glasses of the Li-P-S-Ha system (Ha represents at least one element selected from halogen elements), and LPS crystallization glasses such as Li ７ P ３ S １１ etc. may be mentioned.

[0087] <Step 3> Step 3 is a step of exhausting the gas after the sulfide solid electrolyte powder is obtained in Step 2. The exhausted gas contains residues. These residues contain at least fine powder of the sulfide solid electrolyte.

[0088] Here, in the first form and the third form, in addition to the fine powder of the sulfide solid electrolyte, a low melting point substance having a melting point of 300°C or lower is further contained.

[0089] Furthermore, in the second form, sulfur is further included in addition to the fine powder of the sulfide solid electrolyte. In this case, the residue may contain other substances besides the fine powder and sulfur, for example, low-melting-point substances other than sulfur with a melting point of 300°C or less. Examples of low-melting-point substances with a melting point of 300°C or less include phosphorus pentasulfide, halogens such as iodine, bromine, and chlorine, and hydrogen halides of these halogens (HCl, HBr, HI).

[0090] In step 3 of this embodiment, specifically as shown in Figures 5, 9, and 13, the sulfide solid electrolyte powder obtained in step 2 is collected in vessels 18, 18', and 18'', and the gas after injection is exhausted through exhaust pipes 19, 19', and 19''.

[0091] The fine particles of sulfide solid electrolyte contained in the exhaust gas refer to powder that is exhausted along with the gas because its particle size is too fine to be collected by vessels 18, 18', 18'' or the second vessels 22, 22', 22'' described later. The fine particles of sulfide solid electrolyte mentioned above cannot be defined in general terms, but for example, they include those with a median system D50 of 100 μm or less on a volume basis.

[0092] In the first form, low-melting-point substances with a melting point of 300°C or less among the residues contained in the exhaust gas are substances that, when present in the exhaust gas, cause the filter to become clogged when the gas is passed through the filter. As a result, continuous production of sulfide solid electrolyte powder becomes difficult using a manufacturing method that utilizes filters.

[0093] The types of low-melting-point substances include sulfur, which has a melting point of 115°C and is therefore at least a low-melting-point substance. Furthermore, when phosphorus pentasulfide is used as the raw material for sulfur, the melting point of phosphorus pentasulfide is 288°C, so unreacted phosphorus pentasulfide may also be included in the residue as a low-melting-point substance. Other substances that may be included in the residue as low-melting-point substances include halogens such as iodine, bromine, and chlorine, and their hydrogen halides (HCl, HBr, HI). In other words, the low-melting-point substance in the first embodiment of this model is at least one selected from sulfur, iodine, bromine, chlorine, hydrogen halides, and phosphorus pentasulfide.

[0094] In step 3 of the first embodiment of this product, the exhaust linear velocity when exhausting gas through the exhaust piping is preferably 10 m / s or more, more preferably 15 m / s or more, and even more preferably 20 m / s or more, from the viewpoint of suppressing the accumulation of low-melting-point substances in the exhaust piping. The upper limit of the exhaust linear velocity is not particularly limited, but may be, for example, 30 m / s or less.

[0095] The temperature at which the gas is exhausted is not particularly limited, and any temperature can be used. However, if the residue is to be captured by a filter, there is a concern that the filter may become clogged by mist of low-melting-point substances contained in the residue, so the above temperature had to be below the melting point of the low-melting-point substances, such as room temperature. In contrast, in the manufacturing method according to this embodiment, as will be described later, an alkali scrubber is used instead of a filter in step 4, so the above temperature can be above the melting point of the low-melting-point substances.

[0096] In the second form, sulfur, among the residues contained in the exhaust gas, is a substance that, when present in the exhaust gas, causes the filter to become clogged when the gas is passed through the filter. This is due to the low melting point of sulfur, which is 115°C. As a result, continuous production of sulfide solid electrolyte powder becomes difficult using a manufacturing method that utilizes filters.

[0097] The temperature at which the gas is exhausted is not particularly limited, and any temperature can be used. However, if the residue is to be captured by a filter, there is a concern that the filter may become clogged by mist containing sulfur and other substances in the residue, so the above temperature had to be below the melting point of sulfur, such as room temperature. In contrast, in the manufacturing method according to the second embodiment of this product, as will be described later, a trap containing molten sulfur is used in step 4 instead of a filter, so the above temperature can be above the melting point of sulfur and other substances.

[0098] In the third form, low-melting-point substances with a melting point of 300°C or less, among the residues contained in the exhaust gas, are substances that cause the filter to become clogged when the exhaust gas is passed through the filter. This is thought to be due to the low-melting-point substances existing in a mist-like state. As a result, continuous production of sulfide solid electrolyte powder becomes difficult using a manufacturing method that utilizes filters.

[0099] In contrast, in the manufacturing method according to the third embodiment of this embodiment, the blockage of the filter can be suppressed by cooling the exhaust piping in the subsequent step 4, which changes the low-melting-point substance from a mist to a dust. Low-melting-point substances contained in the residue tend to exist as a mist in the exhausted gas when their melting point is 300°C or lower, which can easily cause filter blockage. Therefore, the manufacturing method according to the third embodiment of this embodiment is effective when the exhausted gas contains residue with a low-melting-point substance of 300°C or lower.

[0100] On the other hand, the lower the melting point of a low-melting-point substance, the more necessary it is to cool the exhausted gas to a low temperature in order to convert it from mist to dust. Therefore, from the viewpoint of the energy required for cooling, the melting point of the low-melting-point substance contained in the residue is preferably 100°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher.

[0101] The types of low-melting-point substances with a melting point of 300°C or less that may be contained in the residue depend on the composition of the obtained sulfide solid electrolyte powder and the raw materials used. In particular, since a sulfur source is always included in the raw materials to obtain sulfide solid electrolyte powder, sulfur is likely to be contained in the residue. Sulfur has a melting point of 115°C and is therefore at least a low-melting-point substance. Furthermore, when phosphorus pentasulfide is used as the raw material for sulfur, the melting point of phosphorus pentasulfide is 288°C, so unreacted phosphorus pentasulfide may also be contained in the residue as a low-melting-point substance. In addition, halogens such as iodine (melting point 114°C) may also be contained in the residue as low-melting-point substances. These components can be turned from a mist to a dust without excessive cooling and are easily captured by a filter without clogging the filter. That is, in the third embodiment of this example, at least one low-melting-point substance selected from sulfur, iodine, and phosphorus pentasulfide is preferred. However, this does not preclude the possibility that the residue in the third embodiment of this model may include other substances with a melting point exceeding 300°C, or low-melting-point substances whose melting point is lower than the temperature of the exhausted gas after cooling, and which remain in a mist-like state without becoming dust even after cooling.

[0102] In step 3 of the third embodiment of this model, the exhaust velocity when exhausting gas through the exhaust pipe is not particularly limited and can be determined appropriately from the viewpoint of suppressing the accumulation of low-melting-point substances in the exhaust pipe and from the viewpoint of cooling the exhaust pipe.

[0103] The temperature at which the gas is exhausted is not particularly limited, and any temperature can be used. However, the gas temperature after the exhaust piping has cooled in the subsequent step 4 will be different from the temperature at which the gas was exhausted.

[0104] In the manufacturing method according to the first to third embodiments of this embodiment, between step 2 and step 3, that is, after obtaining the sulfide solid electrolyte powder in step 2 and before exhausting the gas after injection in step 3, the gas after injection may pass through the pipes 20, 20', 20'' connected to the chamber 15, as shown in Figures 6, 10, and 14, and then through the separation units 21, 21', 21''. This makes it possible to separate the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection.

[0105] The separation units 21, 21', and 21'' recover the sulfide solid electrolyte powder into the second vessels 22, 22', and 22'', thereby increasing the recovery rate. In other words, the proportion of fine sulfide solid electrolyte powder in the residue contained in the gas is reduced. In this case, in step 3, the gas after injection, from which the residue has been reduced, is exhausted through the exhaust pipes 19, 19', and 19'' connected to the separation units 21, 21', and 21''.

[0106] The separation of the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection in the separation units 21, 21', and 21'' is preferably carried out by gravity, inertia, or centrifugal means. Of these, centrifugal means is even more preferable from the viewpoint of dust collection efficiency. When separation is carried out by such separation units 21, 21', and 21'', the fine particles of the sulfide solid electrolyte cannot be defined in general terms, but for example, the median system D50 on a volume basis can be made to be about 5 μm or less.

[0107] <Step 4> Step 4 is a step to remove the residue contained in the gas exhausted in Step 3. In the first form, the removal of the above residue is carried out by an alkaline scrubber, in the second form by a trap containing molten sulfur, and in the third form by a filter. In the third form, the exhausted gas is cooled by a cooling device provided in the exhaust piping before being introduced into the filter, and then the residue is removed.

[0108] Figure 7 shows one embodiment of the alkali scrubber in the first embodiment. The gas containing the residue, which is exhausted in step 3, is introduced into the alkali scrubber 30 through the exhaust pipe 19.

[0109] The gas containing residue that enters the alkaline scrubber 30 comes into contact with the alkaline solution 32 being sprayed in the washing tower 31, allowing the residue to be separated from the gas and removed. As a result, gas that does not contain residue, or has a very reduced percentage of residue, can be discharged to the outside through the exhaust port 38.

[0110] When sulfur is contained in the residue, the sulfur separated from the gas by contacting the sprayed alkaline solution 32 does not dissolve in water. Therefore, it is preferable to precipitate and recover it at the bottom of the alkaline solution 32 in the circulation tank 33.

[0111] The sulfide solid electrolyte and fine powder of phosphorus pentasulfide contained in the residue may react with water to generate hydrogen sulfide (H ２ S). In this case, it is neutralized and removed with the sprayed alkaline solution 32. Iodine and hydrogen halide contained in the residue are easily dissolved in an alkaline aqueous solution.

[0112] In the alkali scrubber 30, the alkaline solution 32 in the circulation tank 33 is sucked up by the circulation pump 35 and sprayed from above the scrubbing tower 31 through the water spray pipe 34. Since the sprayed alkaline solution 32 returns to the circulation tank 33, it can be used for spraying again. Also, since the pH of the alkaline solution 32 in the circulation tank 33 can be measured by the pH meter 37, when the pH value of the alkaline solution 32 decreases due to separating the residue from the gas, the pH can be controlled within a certain range by supplying a new alkaline solution from the alkali tank 36.

[0113] From the viewpoint of capturing hydrogen sulfide among the residues, the pH of the alkaline solution inside the alkali scrubber is preferably 11 or more, more preferably 12 or more, and even more preferably 12.5 or more. The upper limit of the pH of the alkaline solution is not particularly limited and may be 14, but from the viewpoint that alkali reacts with carbon dioxide in the air to form and precipitate carbonates, it may also be 13 or less.

[0114] The above alkaline solution is not particularly limited as long as it can separate the residue from the gas. For example, sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ２ ) etc. can be mentioned. Among them, potassium hydroxide is preferable from the viewpoint of the solubility of the neutralization product. The neutralization product includes, for example, Na ２ S, K ２ S, Na ２ CO ３ , K ２ CO ３ etc.

[0115] The washing tower 31 of the alkaline scrubber 30 may be filled with packing material 39 as shown in Figure 8. The packing material 39 allows the sprayed alkaline solution 32 to remain in the space of the washing tower 31 for a longer time before it falls into the circulation tank 33. This increases the gas-liquid contact efficiency between the gas containing the residue that is exhausted and introduced into the alkaline scrubber 30 and the alkaline solution 32, thereby promoting the separation of the residue.

[0116] The filler 39 can be any conventionally known material, such as irregular fillers like Raschig rings or regular fillers like Melapack. The filler 39 can be any material, such as resin, ceramics, or stainless steel. Examples of resins include polypropylene (PP), polyvinyl chloride (PVC), and fluororesin, and is not particularly limited.

[0117] In the second form, as shown in Figure 9, the trap 30' incorporates molten sulfur 31'. Since the exhaust pipe 19' and the trap 30' are connected, the gas containing the residue exhausted in step 3 passes through the exhaust pipe 19' and is introduced into the trap 30'.

[0118] The gas containing the residue that enters the trap 30' comes into contact with the molten sulfur 31', and the residue contained in the exhausted gas is captured within the trap 30'. More specifically, by bubbling the gas into the molten sulfur 31', the fine particles of sulfide solid electrolyte from the residue are captured by solid-liquid separation as they settle at the bottom of the molten sulfur 31'. In addition, the sulfur from the residue is captured by dissolving in the molten sulfur 31'. As a result, the residue can be separated from the gas and removed. Consequently, gas that does not contain residue, or has a very reduced percentage of residue, can be discharged to the outside through the piping 32'.

[0119] The temperature of the molten sulfur 31' is preferably 115 to 300°C. Here, the gas discharged to the outside through the trap 30' and the pipe 32' contains sulfur equivalent to the sulfur vapor pressure at the temperature of the molten sulfur 31' in the trap 30'. In other words, the lower the temperature of the molten sulfur, the lower the sulfur concentration in the gas discharged to the outside through the pipe 32'. Thus, from the viewpoint of reducing the sulfur concentration in the gas discharged to the outside through the pipe 32', the temperature of the molten sulfur 31' is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 130°C or lower. Furthermore, there is no particular lower limit, but since the melting point of sulfur is 115°C, the temperature of the molten sulfur 31' is 115°C or higher, and may also be 130°C or higher. Furthermore, when the temperature of the molten sulfur 31' is 115°C, the sulfur concentration in the gas discharged to the outside is 0.16 ppm by mass; when it is 130°C, the sulfur concentration is 0.34 ppm by mass; when it is 150°C, the sulfur concentration is 0.87 ppm by mass; and when it is 300°C, the sulfur concentration is 500 ppm by mass.

[0120] The trap 30' may be connected to a tank 40' via piping 41', as shown in Figure 11. This allows for the removal of the overflowing molten sulfur even if the volume of molten sulfur 31' increases due to the capture of residue, enabling more stable continuous production with less pressure fluctuation.

[0121] Furthermore, in the manufacturing method according to this embodiment, as shown in Figure 12, the separation unit 21' shown in Figure 10 and the tank 40' shown in Figure 11 may be connected together. This increases the recovery rate of the sulfide solid electrolyte powder, and even if the volume of molten sulfur 31' increases due to the capture of residue, the overflowing molten sulfur can be removed, enabling more stable continuous production with less pressure fluctuation.

[0122] In the third embodiment, in step 4, the gas linear velocity passing through the filter is preferably 5 m / min or less, preferably 2 m / min or less, and more preferably 1.5 m / min or less, from the viewpoint of effectively capturing the dust-like residue. The lower limit of the gas linear velocity passing through the filter is not particularly limited, but may be, for example, 0.1 m / min or more.

[0123] As shown in Figure 13, the exhaust pipe 19'' is equipped with a cooling device 30''. This cooling device 30'' cools the exhaust gas in the exhaust pipe 19'', and cools any mist-like low-melting-point substances contained in the gas. Since low-melting-point substances turn from mist to dust when cooled below their melting point, even if the dust-like low-melting-point substances are captured by the filter 40'', the filter 40'' does not become blocked, allowing for continuous operation. As a result, gas that contains no residue or has a very reduced percentage of residue can be discharged to the outside through the pipe 41''.

[0124] If the residue contains sulfur, since the melting point of sulfur is 115°C, it is preferable to use the cooling device 30'' to keep the gas temperature in the exhaust pipe 19'' below 115°C. If the residue contains iodine, since the melting point of iodine is 114°C, it is preferable to use the cooling device 30'' to keep the gas temperature in the exhaust pipe 19'' below 114°C. If the residue contains phosphorus pentasulfide, since the melting point of phosphorus pentasulfide is 288°C, it is preferable to use the cooling device 30'' to keep the gas temperature in the exhaust pipe 19'' below 288°C.

[0125] Thus, although it varies depending on the components that make up the residue contained in the exhaust gas and the components that have been removed, the temperature of the gas after being cooled by the cooling device 30'' is preferably, for example, 50 to 150°C. Here, from the viewpoint of turning many of the components contained in the residue into dust, the temperature of the gas is preferably 150°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and still more preferably 80°C or lower. Furthermore, from the viewpoint of not liquefying low-boiling-point substances such as bromine, chlorine, and hydrogen halides contained in the exhaust gas, the temperature of the gas is preferably 50°C or higher, more preferably 60°C or higher, and still more preferably 70°C or higher.

[0126] The cooling device 30'' provided in the exhaust piping 19'' for cooling the exhausted gas is not particularly limited as long as it can cool the exhausted gas to the desired temperature. For example, the cooling device 30'' can be a spiral heat exchanger, a multi-tube heat exchanger, a plate heat exchanger, a fin-tube heat exchanger, etc. Among these, a spiral heat exchanger is preferred from the viewpoint of preventing scaling due to mist adhesion.

[0127] After cooling, the exhausted gas is filtered to capture residue, removing the residue from the gas. The filter is not particularly limited, but examples include bag filters, cartridge filters, and capsule filters. Among these, bag filters are preferred from the viewpoint of longer-term continuous operation.

[0128] Thus, in one embodiment of the manufacturing method according to this embodiment, by using an alkali scrubber (first form) or a trap containing molten sulfur (second form) in step 4, the residue contained in the gas after injection for cooling, solidifying, and pulverizing the molten liquid can be removed and discharged to the outside without using a filter. As a result, continuous production of sulfide solid electrolyte powder becomes possible without worrying about filter clogging. Furthermore, in a third form, which is another embodiment of the manufacturing method according to this embodiment, the gas exhausted in step 4 is cooled to turn the low-melting-point substance, which was in mist form in the residue, into dust before being captured by a filter. This allows for the removal of the residue contained in the gas after injection for cooling, solidifying, and pulverizing the molten liquid without clogging the filter, and discharge to the outside, thus enabling continuous production of sulfide solid electrolyte powder.

[0129] 《Apparatus for Manufacturing Sulfide Solid Electrolyte Powder》 The first embodiment of the apparatus for manufacturing sulfide solid electrolyte powder according to this embodiment comprises: a furnace body that heats and melts sulfide solid electrolyte raw material to obtain a melt; a chamber that injects gas into the melt discharged from the furnace body to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for recovering the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and an alkali scrubber. Here, the exhaust pipe is connected to the alkali scrubber. The above manufacturing apparatus corresponds to the first embodiment of the method for manufacturing sulfide solid electrolyte powder according to this embodiment.

[0130] A second embodiment of the apparatus for producing sulfide solid electrolyte powder according to this embodiment comprises: a furnace body that heats and melts sulfide solid electrolyte raw material to obtain a melt; a chamber that injects gas into the melt discharged from the furnace body to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for collecting the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and a trap containing molten sulfur. Here, the exhaust pipe is connected to the trap. The above-described apparatus corresponds to the second embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment.

[0131] A third embodiment of the apparatus for producing sulfide solid electrolyte powder according to this embodiment comprises: a furnace body that heats and melts sulfide solid electrolyte raw material to obtain a melt; a chamber that injects gas into the melt discharged from the furnace body to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; a vessel for collecting the obtained sulfide solid electrolyte powder; an exhaust pipe for exhausting the gas after injection; and a filter for removing residue contained in the exhausted gas. Here, the exhaust pipe is connected to the filter and is equipped with a cooling device. The residue contained in the exhausted gas includes fine sulfide solid electrolyte powder and low-melting-point substances with a melting point of 300°C or less. However, as the exhaust pipe is cooled by the cooling device, the low-melting-point substances that pass through the exhaust pipe change from a mist to a dust. As a result, the fine sulfide solid electrolyte powder and the low-melting-point substances in dust form are captured by the filter without clogging the filter. The above-described apparatus corresponds to the third embodiment of the method for producing sulfide solid electrolyte powder according to this embodiment.

[0132] The manufacturing apparatus according to this embodiment can be used to carry out the above-described method for producing a sulfide solid electrolyte, and the contents of the corresponding embodiments described in the section "Method for producing sulfide solid electrolyte powder" can be directly applied.

[0133] In other words, the manufacturing apparatus according to this embodiment consists of a part for obtaining sulfide solid electrolyte powder from sulfide solid electrolyte raw material (see the left side of Figures 5, 9, and 13), and an alkali scrubber 30, a trap 30', and a filter 40'' for separating residue from the exhausted gas after injection, all connected by exhaust pipes 19, 19' (exhaust pipe 19'' equipped with a cooling device 30'' for the filter 40'').

[0134] Specifically, as shown in Figures 4, 5, 9, and 13, the system for obtaining sulfide solid electrolyte powder from sulfide solid electrolyte raw materials includes furnace bodies 10, 10', and 10'' that heat and melt the sulfide solid electrolyte raw materials to obtain a melt, chambers 15, 15', and 15'' that inject gas into the melt discharged from the furnace bodies 10, 10', and 10'' to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder, and vessels 18, 18', and 18'' that collect the obtained sulfide solid electrolyte powder.

[0135] A heating section (not shown) for heating the furnace bodies 10, 10', and 10'' is provided for the purpose of performing the heating and melting described in the section on "Method for producing sulfide solid electrolyte powder," and its configuration is not particularly limited.

[0136] The manufacturing apparatus according to this embodiment may include a raw material supply unit (not shown) for supplying sulfide solid electrolyte raw materials to furnace bodies 10, 10', and 10'', and the configuration is not particularly limited. Furthermore, the raw material supply unit may continuously supply sulfide solid electrolyte raw materials into furnace bodies 10, 10', and 10'', or it may quantitatively supply sulfide solid electrolyte raw materials into furnace bodies 10, 10', and 10'', or it may do both.

[0137] The manufacturing apparatus according to this embodiment may include a sulfur supply unit (not shown) for supplying a sulfur source or sulfur vapor as described in the section "Method for Manufacturing Sulfide Solid Electrolyte Powder," and its configuration is not particularly limited. Furthermore, the raw material supply unit and the sulfur supply unit may use different supply ports or the same supply port.

[0138] The discharge sections 13, 13', and 13'' in the manufacturing apparatus according to this embodiment are provided for discharging the molten material obtained by heating and melting the sulfide solid electrolyte raw material in the furnace bodies 10, 10', and 10'' from the furnace bodies 10, 10', and their configuration is not particularly limited. The discharge sections 13, 13', and 13'' may also be configured to continuously discharge the molten material obtained by heating and melting the sulfide solid electrolyte raw material in the furnace bodies 10, 10', and 10'', as described in the section on "Method for Manufacturing Sulfide Solid Electrolyte Powder".

[0139] As described in the section "Method for Manufacturing Sulfide Solid Electrolyte Powder," the manufacturing apparatus according to this embodiment may also be equipped with melt outlets 14, 14', 14'' for allowing the melt discharged from the discharge sections 13, 13', 13'' to flow to the gas injection sections 16, 16', 16'', and the configuration is not particularly limited.

[0140] The gas injection units 16, 16', and 16'' described above are provided for injecting gas into the molten material discharged from the discharge units 13, 13', and 13'' to cool, solidify, and pulverize it, as explained in the section on "Method for Manufacturing Sulfide Solid Electrolyte Powder," and their configuration is not particularly limited. The gas injection units 16, 16', and 16'' may also be provided within the chambers 15, 15', and 15'' as described in the section on "Method for Manufacturing Sulfide Solid Electrolyte Powder."

[0141] As described in the section "Method for producing sulfide solid electrolyte powder," the manufacturing apparatus according to this embodiment may also include a reheating unit (not shown) for reheating the sulfide solid electrolyte powder obtained by cooling in the gas injection units 16, 16', and 16'', and the configuration is not particularly limited.

[0142] In the manufacturing apparatus according to this embodiment, the obtained sulfide solid electrolyte is recovered in vessels 18, 18', and 18''. Meanwhile, the gas after injection is exhausted, and for this purpose, exhaust pipe 19 is connected to an alkali scrubber 30 (first form), exhaust pipe 19' is connected to a trap 30' (second form), and exhaust pipe 19'' is connected to a filter 40'' (third form).

[0143] In the first embodiment (Figure 5), the chamber 15 and the alkali scrubber 30 are connected by an exhaust pipe 19. However, as shown in Figure 6, a separation unit 21 and a second vessel 22 may be further provided between the chamber 15 and the exhaust pipe 19.

[0144] The separation unit 21 separates the sulfide solid electrolyte powder that could not be recovered in the vessel 18 and is contained in the gas after injection from at least a portion of the residue contained in the gas after injection, and the separated sulfide solid electrolyte powder is recovered in the second vessel 22. Here, the above residue includes fine sulfide solid electrolyte powder and low melting point substances with a melting point of 300°C or less, as explained in the section on "Method for producing sulfide solid electrolyte powder".

[0145] The separation unit 21 may be any of the following dust collection means: a gravity-type dust collector, an inertial-force dust collector, or a centrifugal dust collector. One or more of these may be used, but from the viewpoint of dust collection efficiency, a centrifugal dust collector is preferred.

[0146] The gas after injection is introduced into the alkali scrubber 30 through the exhaust pipe 19. As described in the section on "Method for Manufacturing Sulfide Solid Electrolyte Powder," the alkali scrubber 30 is equipped with a washing tower 31 and an exhaust port 38. In the washing tower 31, the residue contained in the gas is separated from the gas and removed by contact with the alkaline solution.

[0147] For contact with the alkaline solution, the alkaline scrubber 30 preferably includes a circulation tank 33, a water spray pipe 34, a circulation pump 35, an alkaline tank 36, and a pH meter 37. The circulation tank 33 is filled with the alkaline solution, and the alkaline solution is sent to the water spray pipe 34 via the circulation pump 35 and sprayed.

[0148] As residue removal continues, the alkaline solution in the circulation tank 33 may be neutralized, causing the pH to decrease. Therefore, the pH of the alkaline solution in the circulation tank 33 is measured using the pH meter 37, and alkaline solution is introduced into the circulation tank 33 from the alkaline tank 36 as needed to maintain the pH within a certain range. For example, the pH may be adjusted to be 11 or higher.

[0149] Depending on the compounds in the removed residue, the manufacturing apparatus according to this embodiment may further include a mechanism (not shown) for recovering precipitated residue to deal with residues that are insoluble in alkaline solutions, such as sulfur.

[0150] The alkaline scrubber 30 may have packing material 39 built into the washing tower 31. The packing material 39 lengthens the path for the sprayed alkaline solution to return to the circulation tank 33. As a result, the contact time between the alkaline solution and the gas containing the residue can be increased, thereby improving the residue removal rate.

[0151] The gas from which the residue has been removed by the washing tower 31 is discharged to the outside through the exhaust port 38.

[0152] In the second embodiment (Figure 9), the chamber 15' and the trap 30' are connected by an exhaust pipe 19', but as shown in Figure 10, a separation unit 21' and a second vessel 22' may be further provided between the chamber 15' and the exhaust pipe 19'.

[0153] The separation unit 21' separates the sulfide solid electrolyte powder that could not be recovered in the vessel 18' and is contained in the gas after injection from at least a portion of the residue contained in the gas after injection, and the separated sulfide solid electrolyte powder is recovered in the second vessel 22'. Here, the above residue includes fine sulfide solid electrolyte powder and sulfur, as explained in the section on "Method for producing sulfide solid electrolyte powder".

[0154] The separation unit 21' may be any of the following dust collection means: a gravity-type dust collector, an inertial-force dust collector, or a centrifugal dust collector. One or more of these may be used, but from the viewpoint of dust collection efficiency, a centrifugal dust collector is preferred.

[0155] The gas after injection is introduced into the trap 30' through the exhaust pipe 19'. The trap 30' contains molten sulfur 31', as explained in the section on "Method for Manufacturing Sulfide Solid Electrolyte Powder". The exhausted gas introduced into the trap 30' through the exhaust pipe 19' comes into contact with the molten sulfur 31', allowing the residue contained in the gas to be separated and removed. Specifically, the fine powder of the sulfide solid electrolyte from the residue settles at the bottom of the molten sulfur 31', and the sulfur is removed by dissolving in the molten sulfur.

[0156] The trap 30' contains molten sulfur 31', but the amount of molten sulfur tends to increase due to the capture of residue. Therefore, as shown in Figures 11 and 12, a tank 40' may be connected to the trap 30' to remove the overflowing molten sulfur. This connection is made, for example, via piping 41'.

[0157] The manufacturing apparatus according to this embodiment may further include a mechanism (not shown) for recovering residues precipitated in the molten sulfur 31', such as fine powder of sulfide solid electrolyte.

[0158] After the residue is captured in the trap 30', the gas is discharged to the outside through the pipe 32'.

[0159] In the third embodiment, Figure 13, the chamber 15'' and the filter 40'' are connected by an exhaust pipe 19'', but as shown in Figure 14, a separation unit 21'' and a second vessel 22'' may be further provided between the chamber 15'' and the exhaust pipe 19''.

[0160] The separation unit 21'' separates the sulfide solid electrolyte powder that could not be recovered in the vessel 18'' and is contained in the gas after injection from at least a portion of the residue contained in the gas after injection, and the separated sulfide solid electrolyte powder is recovered in the second vessel 22''. Here, the above residue includes fine sulfide solid electrolyte powder and low melting point substances with a melting point of 300°C or less, as explained in the section on "Method for producing sulfide solid electrolyte powder".

[0161] The separation unit 21'' may be any of the following dust collection means: a gravity dust collector, an inertial dust collector, or a centrifugal dust collector. One or more of these may be used, but from the viewpoint of dust collection efficiency, a centrifugal dust collector is preferred.

[0162] The gas after injection passes through the exhaust pipe 19'' and is introduced into the filter 40'' after being cooled by the cooling device 30'' provided in the exhaust pipe 19''. As a result, the low-melting-point substance changes from a mist to a dust and is captured in the filter 40'' together with the fine powder of the sulfide solid electrolyte. As described in the section on "Method for producing sulfide solid electrolyte powder", a bag filter is preferred for the filter 40''.

[0163] The gas from which the residue has been removed by the filter 40'' is discharged to the outside through the pipe 41''.

[0164] It should be noted that the present invention is not limited to the embodiments described above, and the components of each embodiment can be combined with each other, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the embodiments described above, and can be modified and improved as appropriate. Furthermore, the material, shape, dimensions, number, and placement of each component in the embodiments described above are arbitrary and not limited as long as they can achieve the present invention.

[0165] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. Examples A1, B1-B3, and C1 are examples, and examples A2-A4 and C2 are comparative examples.

[0166] Example A1: Preparation of sulfide solid electrolyte raw materials. Li ２ S, P ２ S ５ The LiCl raw material powders were blended in a ratio of 1.9:0.5:1.6 (mol ratio). This mixture of raw material powders was placed in a heat-resistant container, and the container was placed in a heating furnace. The mixture was then heat-treated for 0.5 hours under conditions of a nitrogen atmosphere with a dew point of -50°C, a pressure of 1 atmosphere, and a temperature of 300°C (heating rate of 5°C / min) to obtain a sulfide solid electrolyte raw material.

[0167] <Heating and melting of sulfide solid electrolyte raw materials> The sulfide solid electrolyte raw materials obtained above and elemental sulfur powder were placed in a heat-resistant container in a ratio of 100:4 (mass ratio) and heated and melted at 730°C for 0.5 hours to obtain a melt. Nitrogen gas was flowed into the heating furnace to maintain a dew point of -50°C.

[0168] <Production of Sulfide Solid Electrolyte Powder> The molten material obtained above was discharged from the discharge nozzle, cooled and solidified at a gas spray pressure of 0.9 MPa, and pulverized. The molten material was then discharged into a sealed chamber maintained at a dew point of -50°C or lower and an oxygen concentration of less than 100 ppm by volume to obtain sulfide solid electrolyte powder. The recovery rate of the sulfide solid electrolyte powder was 22.2%.

[0169] <Separation of sulfide solid electrolyte powder and residue> The gas after injection was introduced through piping into a cyclone-type centrifugal separation unit, and the sulfide solid electrolyte powder that could not be recovered above was recovered into the chamber. The recovery rate of the sulfide solid electrolyte powder at this stage was 74.3%.

[0170] <Removal of Residue from Exhausted Gas> Next, the gas was exhausted at an exhaust linear velocity of 15 m / s and introduced into the alkaline scrubber. The alkaline solution in the alkaline scrubber was potassium hydroxide with a pH of 12.5. Then, the gas discharged to the outside from the exhaust of the alkaline scrubber was analyzed, and H ２ The sulfur (S) concentration was measured using a hydrogen sulfide meter (ANALYTICAL TECHNOLOGY, Q45) and was found to be below the detection limit. Furthermore, no deposits originating from the residue were found in either the exhaust piping or the exhaust port, confirming that continuous production of sulfide solid electrolyte powder is possible. The process from the chamber to the exhaust piping was carried out at 150°C. In addition, the presence of fine sulfide solid electrolyte powder and sulfur in the residue was confirmed by energy-dispersive X-ray fluorescence spectroscopy and Raman spectroscopy.

[0171] Example A2: The sulfide solid electrolyte powder was manufactured in the same manner as in Example A1, except that an alkaline trap was used instead of an alkaline scrubber to remove the residue. The alkaline trap consisted of an exhaust pipe connected to a sodium hydroxide aqueous solution with a pH of 12.5. As a result, although fine sulfide solid electrolyte residue was captured in the alkaline trap with a recovery rate of 1.5%, the outlet of the exhaust pipe in contact with the alkaline trap became clogged with sulfur because the sulfur in the residue is insoluble in water. Therefore, continuous production of sulfide solid electrolyte powder is difficult.

[0172] Example A3: Sulfide solid electrolyte powder was manufactured in the same manner as in Example A2, except that the exhaust linear velocity in the exhaust piping was changed from 15 m / s to 0.3 m / s. As a result, although fine sulfide solid electrolyte residue was captured in the alkali trap with a recovery rate of 0.4%, the outlet of the exhaust piping in contact with the alkali trap became clogged with sulfur because the sulfur in the residue is insoluble in water. Furthermore, due to the low exhaust linear velocity, the volume of residue was also confirmed inside the exhaust piping. Therefore, continuous production of sulfide solid electrolyte powder is difficult.

[0173] Example A4: The sulfide solid electrolyte powder was manufactured in the same manner as in Example A1, except that the exhaust linear velocity was set to 0.5 m / s and a bag filter was used instead of an alkali scrubber to attempt to remove the residue. As a result, a yellowish viscous substance was observed to the naked eye on the surface of the bag filter, and continuous production of the sulfide solid electrolyte powder was not possible due to abnormal pressure.

[0174] Based on the above results, the present invention enables continuous production of sulfide solid electrolyte powder in a manufacturing method that cools and solidifies a melt by gas injection and then pulverizes it.

[0175] Example B1: Preparation of sulfide solid electrolyte raw materials. Li ２ S, P ２ S ５ The LiCl raw material powders were blended in a ratio of 1.9:0.5:1.6 (mol ratio). This mixture of raw material powders was placed in a heat-resistant container, and the container was placed in a heating furnace. The mixture was then heat-treated for 0.5 hours under conditions of a nitrogen atmosphere with a dew point of -50°C, a pressure of 1 atmosphere, and a temperature of 300°C (heating rate of 5°C / min) to obtain a sulfide solid electrolyte raw material.

[0176] <Heating and melting of sulfide solid electrolyte raw materials> The sulfide solid electrolyte raw materials obtained above and elemental sulfur powder were placed in a heat-resistant container in a ratio of 100:4 (mass ratio) and heated and melted at 730°C for 0.5 hours to obtain a melt. Nitrogen gas was flowed into the heating furnace to maintain a dew point of -50°C.

[0177] <Production of Sulfide Solid Electrolyte Powder> The molten material obtained above was discharged from the discharge nozzle, cooled and solidified at a gas spray pressure of 0.9 MPa, and pulverized. The molten material was then discharged into a sealed chamber maintained at a dew point of -50°C or lower and an oxygen concentration of less than 100 ppm by volume to obtain sulfide solid electrolyte powder. The recovery rate of the sulfide solid electrolyte powder was 22.2%.

[0178] <Separation of sulfide solid electrolyte powder and residue> The gas after injection was introduced through piping into a cyclone-type centrifugal separation unit, and the sulfide solid electrolyte powder that could not be recovered above was recovered into the chamber. The recovery rate of the sulfide solid electrolyte powder at this stage was 74.3%.

[0179] <Removal of Residue from Exhausted Gas> Next, the gas is exhausted at a flow rate of 1000 L / min and introduced into a trap containing molten sulfur. The temperature of the molten sulfur is set to 150°C. As a result, a precipitate containing fine particles of sulfide solid electrolyte is formed in the molten sulfur in the trap. Furthermore, the gas discharged to the outside from the piping connected to the trap contains a very small amount of sulfur, at 0.87 ppm by mass, which is the sulfur vapor pressure at the temperature of the molten sulfur (150°C). In this way, sulfide solid electrolyte powder can be continuously produced.

[0180] Example B2: The sulfide solid electrolyte powder is produced in the same manner as in Example B1, except that the temperature of the molten sulfur in the trap is changed to 130°C. As a result, a precipitate containing fine sulfide solid electrolyte powder is formed in the molten sulfur in the trap. Furthermore, the gas discharged to the outside from the piping connected to the trap contains a very small amount of sulfur, which is 0.34 ppm by mass as the sulfur vapor pressure at the temperature of the molten sulfur, 130°C. In this way, sulfide solid electrolyte powder can be produced continuously.

[0181] Example B3: The sulfide solid electrolyte powder is produced in the same manner as in Example B1, except that the temperature of the molten sulfur in the trap is changed to 115°C. As a result, a precipitate containing fine sulfide solid electrolyte powder is formed in the molten sulfur in the trap. Furthermore, the gas discharged to the outside from the piping connected to the trap contains a very small amount of sulfur, which is 0.16 ppm by mass, representing the sulfur vapor pressure at the temperature of the molten sulfur (115°C). In this way, sulfide solid electrolyte powder can be produced continuously.

[0182] Based on the above results, the present invention enables continuous production of sulfide solid electrolyte powder in a manufacturing method that cools and solidifies a melt by gas injection and then pulverizes it.

[0183] Example C1: Preparation of sulfide solid electrolyte raw materials. Li ２ S, P ２ S ５ The LiCl raw material powders were blended in a ratio of 1.9:0.5:1.6 (mol ratio). This mixture of raw material powders was placed in a heat-resistant container, and the container was placed in a heating furnace. The mixture was then heat-treated for 0.5 hours under conditions of a nitrogen atmosphere with a dew point of -50°C, a pressure of 1 atmosphere, and a temperature of 300°C (heating rate of 5°C / min) to obtain a sulfide solid electrolyte raw material.

[0184] <Heating and melting of sulfide solid electrolyte raw materials> The sulfide solid electrolyte raw materials obtained above and elemental sulfur powder were placed in a heat-resistant container in a ratio of 100:4 (mass ratio) and heated and melted at 730°C for 0.5 hours to obtain a melt. Nitrogen gas was flowed into the heating furnace to maintain a dew point of -50°C.

[0185] <Production of Sulfide Solid Electrolyte Powder> The molten material obtained above was discharged from the discharge nozzle, cooled and solidified at a gas spray pressure of 0.9 MPa, and pulverized. The molten material was then discharged into a sealed chamber maintained at a dew point of -50°C or lower and an oxygen concentration of less than 100 ppm by volume to obtain sulfide solid electrolyte powder. The recovery rate of the sulfide solid electrolyte powder was 22.2%.

[0186] <Separation of sulfide solid electrolyte powder and residue> The gas after injection was introduced through piping into a cyclone-type centrifugal separation unit, and the sulfide solid electrolyte powder that could not be recovered above was recovered into the chamber. The recovery rate of the sulfide solid electrolyte powder at this stage was 74.3%.

[0187] <Removal of Residue from Exhausted Gas> Next, the gas was exhausted and passed through the bag filter at a gas linear velocity of 0.5 m / min. At this time, the temperature of the exhausted gas was cooled to approximately room temperature by the cooling device installed in the exhaust piping. In practice, the temperature of the exhausted gas was initially set to approximately room temperature without cooling. As a result, the differential pressure before and after gas exhaust was 1.2 kPa, and only powder was adhering to the surface of the bag filter; no blockage by mist-like low-melting-point substances was observed. This can be considered equivalent to the result obtained when the exhaust piping was cooled to room temperature. It was confirmed that the powder adhering to the bag filter contained fine powder of sulfide solid electrolyte and sulfur. From these results, it was confirmed that sulfide solid electrolyte powder can be continuously produced.

[0188] Example C2: The sulfide solid electrolyte powder is manufactured in the same manner as in Example C1, except that the exhaust gas temperature is cooled to 150°C by a cooling device in the exhaust piping. In practice, the exhaust gas temperature was set to 150°C without cooling, but as a result the differential pressure before and after gas exhaust exceeded 15 kPa, causing the device to shut down due to an abnormal pressure. A viscous substance, not powder, was found adhering to the surface of the bag filter, indicating blockage of the bag filter. This can be considered equivalent to the result when the exhaust piping is cooled to 150°C. Note that the temperature of the exhaust gas after cooling, 150°C, is higher than the melting point of sulfur, a low-melting-point substance (115°C). The sulfur did not change into dust but remained in mist form and was captured by the bag filter, causing the bag filter to become blocked.

[0189] Based on the above results, the present invention enables continuous production of sulfide solid electrolyte powder in a manufacturing method that cools and solidifies a melt by gas injection and then pulverizes it.

[0190] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0191] This application is based on Japanese Patent Application No. 2024-226351, Japanese Patent Application No. 2024-226352, and Japanese Patent Application No. 2024-226353, filed on December 23, 2024, the contents of which are incorporated herein by reference.

[0192] 10 Furnace body 11 Molten 12 Sulfide solid electrolyte raw material 13 Discharge section 14 Molten outflow section 15 Chamber 16 Gas injection section 17 Gas 18, 18', 18'' Vessel 19, 19', 19'' Exhaust piping 20, 20', 20'' Piping 21, 21', 21'' Separation unit 22, 22', 22'' Second vessel 30 Alkali scrubber 31 Washing tower 32 Alkali solution 33 Circulation tank 34 Sprinkler pipe 35 Circulation pump 36 Alkali tank 37 pH meter 38 Outlet 39 Packing material 30' Trap 31' Molten sulfur 32' Piping 40' Tank 41' Piping 30'' Cooling device 40'' Filter 41'' Piping

Claims

1. A method for producing sulfide solid electrolyte powder, comprising: heating and melting a sulfide solid electrolyte raw material in a furnace to obtain a melt; injecting gas into the melt while discharging the melt from the furnace to cool, solidify, and pulverize the melt to obtain sulfide solid electrolyte powder; exhausting the gas after injection; and removing the residue contained in the exhausted gas, wherein the residue contains at least fine powder of sulfide solid electrolyte.

2. The method for producing sulfide solid electrolyte powder according to claim 1, wherein the residue further contains a low-melting-point substance having a melting point of 300°C or less, and the residue is removed by an alkaline scrubber.

3. The method for producing a sulfide solid electrolyte powder according to claim 1, wherein the residue further contains sulfur, and the residue is removed by contacting the exhausted gas with molten sulfur.

4. The method for producing sulfide solid electrolyte powder according to claim 1, wherein the residue further contains a low-melting-point substance having a melting point of 300°C or less, the residue is removed by a filter, and the mist-like low-melting-point substance contained in the residue is cooled to become dust and then captured by the filter.

5. The method for producing a sulfide solid electrolyte powder according to claim 2, wherein the low melting point substance is at least one selected from sulfur, iodine, bromine, chlorine, hydrogen halide, and phosphorus pentasulfide.

6. The method for producing a sulfide solid electrolyte powder according to claim 2 or 5, further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection.

7. The method for producing sulfide solid electrolyte powder according to claim 6, wherein the separation is performed by centrifugal force.

8. The method for producing sulfide solid electrolyte powder according to claim 2 or 5, wherein the exhaust linear velocity during exhaust is 10 m / s or more.

9. The method for producing sulfide solid electrolyte powder according to claim 2 or 5, wherein the pH of the alkaline solution inside the alkali scrubber is 11 or higher.

10. The method for producing a sulfide solid electrolyte powder according to claim 3, further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection.

11. The method for producing sulfide solid electrolyte powder according to claim 10, wherein the separation is performed by centrifugal force.

12. The method for producing a sulfide solid electrolyte powder according to claim 4, wherein the low melting point substance is at least one selected from sulfur, iodine, and phosphorus pentasulfide.

13. A method for producing a sulfide solid electrolyte powder according to claim 4 or 12, further comprising separating the sulfide solid electrolyte powder from at least a portion of the residue contained in the gas after injection, after obtaining the sulfide solid electrolyte powder and before exhausting the gas after injection.

14. The method for producing sulfide solid electrolyte powder according to claim 13, wherein the separation is performed by centrifugal force.

15. The method for producing sulfide solid electrolyte powder according to claim 4 or 12, wherein the filter is a bag filter.

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