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

Abstract

Provided is a method for producing a sulfide-based solid electrolyte, with which it is possible to stably and continuously produce a sulfide-based solid electrolyte. The problem is solved by a production method in which a sulfide-based solid electrolyte raw material is supplied into a furnace body (10), the sulfide-based solid electrolyte raw material is heated and melted, and the resulting melt (11) is discharged to the outside of the furnace body (10) through a heated flow path (12) and cooled.

Description

Technical Field

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

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

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

[0004] As a synthesis method of the sulfide-based solid electrolyte, a method of heating and melting a sulfide-based solid electrolyte raw material to prepare a melt and cooling and solidifying it can be cited. However, there is a problem that gaseous volatile components generated from the melt during cooling and solidification condense and hinder stable production. In particular, in a manufacturing method in which a sulfide-based solid electrolyte raw material is continuously supplied into a furnace body and the obtained melt is continuously discharged for cooling and solidification, there is a problem that the melt condenses near the discharge port and hinders stable production.

[0005] Patent Document 1 discloses a method for manufacturing a sulfide-based lithium ion conductive solid electrolyte. After mixing the constituent compounds of the sulfide-based lithium ion conductive solid electrolyte in a predetermined stoichiometric ratio, the mixture is heated and melted in a state where sulfur is in excess.

[0006] In addition, Patent Document 2 discloses a method for manufacturing a lithium ion conductive material, which is characterized by including: (1) a step of melting a composite compound containing lithium, phosphorus, and sulfur as components to vitrify it, and (2) a step of obtaining a sulfide glass by rapidly cooling the molten glass.

[0007] In addition, Patent Document 3 discloses a method for manufacturing a solid electrolyte glass by compressing a raw material input section, heating and melting the raw material, cooling it, and continuously discharging it.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent No. 3284215 Gazette

[0011] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2012-43654

[0012] Patent Document 3: Japanese Patent Publication No. 5640665 Summary of the Invention

[0013] However, in the technologies disclosed in Patent Documents 1 and 2 described above, it is impossible to suppress the generation of gas from the above-mentioned melt, and it is impossible to sufficiently solve the above-mentioned problems caused by the condensate of the gas. In addition, in the technology disclosed in Patent Document 3 described above, the structure of the device is complicated, and it is easy to solidify and block the flow path during the cooling of the raw material, making it difficult to control the entire device.

[0014] Therefore, an object of the present invention is to solve the above-mentioned problems caused by the condensate of the gas generated from the melt of the sulfide-based solid electrolyte raw material, and to provide a manufacturing method and a manufacturing device for a sulfide-based solid electrolyte capable of stably and continuously producing a sulfide-based solid electrolyte.

[0015] As a result of intensive research by the present inventors, it has been found that by heating the flow path used for discharging when discharging the melt of the sulfide-based solid electrolyte raw material from the furnace body, the above-mentioned problems can be solved, and thus the present invention has been completed.

[0016] That is, the present invention relates to the following [1] to

[12] .

[0017] [1] A method for manufacturing a sulfide-based solid electrolyte, comprising supplying a sulfide-based solid electrolyte raw material into a furnace body, heating and melting the above-mentioned sulfide-based solid electrolyte raw material, and discharging the obtained melt to the outside of the above-mentioned furnace body through a heated flow path and cooling it.

[0018] [2] The method for manufacturing a sulfide-based solid electrolyte according to the above [1], wherein the above-mentioned flow path has a throttling portion.

[0019] [3] The method for manufacturing a sulfide-based solid electrolyte according to the above [2], wherein the shape of the above-mentioned throttling portion is a nozzle shape.

[0020] [4] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein a heat insulation layer is provided between the above-mentioned furnace body and the above-mentioned flow path.

[0021] [5] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the heating temperature of the above-mentioned flow path is 500 °C or higher.

[0022] [6] The method for manufacturing a sulfide-based solid electrolyte according to the above [1] or [2], wherein the supply of the sulfide-based solid electrolyte raw material into the above-mentioned furnace body and the discharge of the above-mentioned melt to the outside of the above-mentioned furnace body are continuously performed.

[0023] [7] The manufacturing method of the sulfide-based solid electrolyte according to [1] or [2] above, wherein the cooling is performed by a twin-roll method.

[0024] [8] The manufacturing method of the sulfide-based solid electrolyte according to [1] or [2] above, wherein the cooling is performed by a gas atomization method.

[0025] [9] A manufacturing apparatus for a sulfide-based solid electrolyte, comprising:

[0026] A furnace body for heating and melting a sulfide-based solid electrolyte raw material, and

[0027] A flow path for discharging the melt obtained by the above heating and melting to the outside of the above furnace body;

[0028] The above flow path is provided with a heating portion for heating the above flow path, and

[0029] A cooling portion for cooling the melt is provided near the downstream end portion of the above flow path.

[0030]

[10] The manufacturing apparatus for a sulfide-based solid electrolyte according to [9] above, wherein the above flow path has a throttling portion.

[0031]

[11] The manufacturing apparatus for a sulfide-based solid electrolyte according to

[10] above, wherein the shape of the above throttling portion is a nozzle shape.

[0032]

[12] The manufacturing apparatus for a sulfide-based solid electrolyte according to any one of [9] to

[11] above, wherein a heat insulating layer is provided between the above furnace body and the above flow path.

[0033] According to the present invention, when discharging the melt of the sulfide-based solid electrolyte raw material from the furnace body, by heating the flow path used for the discharge, generation of gas from the above melt is suppressed, the above problems caused by condensates derived from the gas are solved, and a manufacturing method and a manufacturing apparatus for a sulfide-based solid electrolyte capable of stably and continuously producing a sulfide-based solid electrolyte can be provided. Brief Description of the Drawings

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

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

[0036] Figure 3 is a cross-sectional schematic view showing another example of a manufacturing apparatus for a sulfide-based solid electrolyte according to an embodiment of the present invention.

[0037] Figure 4 It is a cross-sectional schematic diagram showing another example of the manufacturing apparatus for a sulfide-based solid electrolyte representing an embodiment of the present invention.

[0038] Figure 5 It is a cross-sectional schematic diagram showing the manufacturing apparatus for a sulfide-based solid electrolyte used in a comparative example. Detailed Embodiments

[0039] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value. In addition, in this specification, "mass" and "weight" are synonymous. In the following drawings, sometimes the same reference numerals are given to components and parts having the same functions for description, and repeated descriptions are omitted or simplified. In addition, the embodiments shown in the drawings are schematically shown for clearly explaining the present invention, and do not necessarily accurately represent the dimensions and ratios of actual apparatuses and the like.

[0040] <Manufacturing Method of Sulfide-Based Solid Electrolyte>

[0041] For the manufacturing method of the sulfide-based solid electrolyte according to an embodiment of the present invention (hereinafter, also referred to as this manufacturing method), it is characterized in that a sulfide-based solid electrolyte raw material is supplied into a furnace body, the sulfide-based solid electrolyte raw material is heated and melted, and the obtained melt is discharged out of the furnace body through a heated flow path and cooled.

[0042] Figure 1 It shows a flowchart of this manufacturing method. In this manufacturing method, first, a sulfide-based solid electrolyte raw material is heated and melted in a furnace body (step S1) to obtain a melt (step S2). The obtained melt is discharged out of the above furnace body through a heated flow path (step S3) and cooled (step S4) to obtain a sulfide-based solid electrolyte (step S5).

[0043] As the furnace body, a known furnace body having a heating part and conventionally used for heating and melting a solid electrolyte raw material can be appropriately used, and the material and size of the furnace body can be arbitrarily selected.

[0044] (Sulfide-Based Solid Electrolyte Raw Material)

[0045] In this manufacturing method, various raw materials can be used as the sulfide-based solid electrolyte raw material (hereinafter, sometimes referred to as this raw material).

[0046] As the raw material, a commercially available sulfide-based solid electrolyte raw material can be used, or a sulfide-based solid electrolyte raw material manufactured from a material can be used. In addition, these sulfide-based solid electrolyte raw materials can also be further subjected to a known pretreatment. That is, the present production method can appropriately include a step of producing the raw material and a step of pretreating the raw material.

[0047] The sulfide-based solid electrolyte raw material is described in detail below. The sulfide-based solid electrolyte raw material generally contains an alkali metal element (R) and sulfur element (S).

[0048] As the alkali metal element (R), lithium element (Li), sodium element (Na) and potassium element (K) can be cited, among which lithium element (Li) is preferred. As the alkali metal element (R), substances (components) containing alkali metal elements such as simple alkali metal elements and compounds containing alkali metal elements can be appropriately used in combination. Among them, as the lithium element, substances (components) containing Li such as simple Li and compounds containing Li can be appropriately used in combination.

[0049] Examples of materials containing lithium element (Li) include 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 nitride (Li 3 As the substance containing lithium element (Li), lithium sulfide is preferably used from the viewpoint of obtaining a sulfide material.

[0050] As the sulfur element (S), a simple substance of S, a compound containing S, or other substances (components) containing S may be used in combination as appropriate.

[0051] Examples of substances containing sulfur (S) include phosphorus trisulfide (P 2 S 3 ), phosphorus pentasulfide (P 2 S 5 ) and other phosphorus sulfides, other sulfur compounds containing phosphorus, elemental sulfur, and compounds containing sulfur. Examples of compounds containing sulfur include H 2 S.C.S. 2 、Na 2 S, iron sulfide (FeS, Fe 2 S 3 , FeS 2 , Fe 1－x S, etc.), bismuth sulfide (Bi2 S 3 ), antimony sulfide (Sb 2 S 3 ), copper sulfide (CuS, Cu 2 S, Cu 1－x S, etc.), tin sulfide (SnS 2 ), tungsten sulfide (WS 2 As a substance containing sulfur element (S), from the viewpoint of obtaining a sulfide material, phosphorus sulfide is preferred, and phosphorus pentasulfide (P 2 S 5 These substances may be used alone or in combination of two or more. It should be noted that phosphorus sulfide is considered to be a compound having both a substance containing S and a substance containing P described later.

[0052] From the viewpoint of improving the ionic conductivity of the obtained sulfide-based solid electrolyte, the raw material preferably further contains phosphorus (P). As phosphorus (P), P alone, P-containing compounds and other P-containing substances (components) can be used in appropriate combination.

[0053] Examples of substances containing phosphorus (P) include phosphorus trisulfide (P 2 S 3 ), phosphorus pentasulfide (P 2 S 5 ) and other phosphorus sulfide, sodium phosphate (Na 3 PO 4 ) and phosphorus compounds such as elemental phosphorus. As the substance containing phosphorus element (P), from the viewpoint of further exerting the effect of the present invention, phosphorus sulfide with high volatility is preferred, and phosphorus pentasulfide (P 2 S 5 ). These substances may be used alone or in combination of two or more.

[0054] This raw material can be obtained as a mixed raw material by, for example, appropriately mixing the above substances according to the composition of the target sulfide-based solid electrolyte. The mixing ratio is not particularly limited. For example, from the viewpoint of improving the ionic conductivity of the obtained sulfide-based solid electrolyte, the molar ratio S / R of the sulfur element (S) relative to the alkali metal element (R) in this raw material is preferably 0.65 / 0.35 or less, and more preferably 0.5 / 0.5 or less. In addition, the mixed raw material is preferably obtained by mixing in a prescribed stoichiometric ratio corresponding to the substance used for mixing. As the above-mentioned mixing method, for example, mixing in a mortar, mixing using a medium such as a planetary ball mill, a pin mill, a powder mixer, and a medium-free mixing such as airflow mixing can be cited.

[0055] As an example of a preferred combination of the alkali metal element and sulfur element contained in this raw material, Li can be cited. 2 S and P 2 S 5 The combination of. When the combination is Li 2 S and P 2 S 5 , the molar ratio of Li to P, Li / P, is preferably 40 / 60 or more, more preferably 50 / 50 or more. In addition, the molar ratio of Li to P, Li / P, is preferably 88 / 12 or less. Further, the molar ratio of Li to P, Li / P, is preferably 40 / 60 to 88 / 12, more preferably 50 / 50 to 88 / 12. By adjusting the mixing ratio, P 2 S 5 is less relative to Li 2 S, thereby easily suppressing the volatilization of the sulfur component and phosphorus component during the heat treatment due to the boiling point of P 2 S 5 being lower than the melting point of Li 2 S.

[0056] On the other hand, since lithium sulfide is expensive, from the viewpoint of suppressing the manufacturing cost of the sulfide-based solid electrolyte, lithium compounds other than lithium sulfide, metallic lithium, etc. can be used. Specifically, in this case, the raw material preferably contains one or more selected from metallic lithium, lithium iodide (LiI), lithium carbonate (Li 2 CO 3 ), lithium sulfate (Li 2 SO 4 ), lithium oxide (Li 2 O) and lithium hydroxide (LiOH) as the Li-containing substances. These substances can be used alone or in combination of two or more.

[0057] This raw material can further contain substances (compounds, etc.) other than the above-mentioned substances according to the composition of the target sulfide-based solid electrolyte or as additives, etc.

[0058] For example, in the case of manufacturing a sulfide-based solid electrolyte containing halogen elements such as F, Cl, Br or I, the raw material preferably contains a halogen element (Ha). In this case, the raw material preferably contains a compound of the halogen element. As the compound containing the halogen element, lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI) and other lithium halides (LiHa), phosphorus halides, phosphoryl halides, sulfur halides, sodium chloride (NaCl) and other sodium halides, barium fluoride (BaF 2 ), barium halides such as barium bromide, boron halides, yttrium chloride (YCl 3 ), yttrium halides such as yttrium iodide, indium chloride (InCl 3) Indium halides such as, zirconium chloride (ZrCl 4 ) Zirconium halides such as, lanthanum fluoride (LaF 2 ) Lanthanum halides and the like. As the compound containing a halogen element, from the viewpoint of the reactivity of the raw material, lithium halide is preferred, and LiCl, LiBr, and LiI are more preferred. These compounds can be used alone or in combination of two or more.

[0059] It should be noted that alkali metal halides such as lithium halide are also compounds containing alkali metal elements such as Li. When this raw material contains an alkali metal halide, a part or all of the alkali metal elements such as Li in this raw material can be derived from the alkali metal halide such as lithium halide.

[0060] When this raw material contains a halogen element (Ha) and a phosphorus element (P), from the viewpoints of improving the ionic conductivity of the obtained sulfide-based solid electrolyte and the like, the molar equivalent of Ha relative to P in this raw material is preferably 0.2 molar equivalent or more, and more preferably 0.5 molar equivalent or more. In addition, from the viewpoint of the stability of the obtained sulfide-based solid electrolyte, the molar equivalent of Ha is preferably 4 molar equivalents or less, and more preferably 3 molar equivalents or less.

[0061] The obtained sulfide-based solid electrolyte can be an amorphous sulfide-based solid electrolyte according to its purpose. From the viewpoint of improving the ease of formation of the amorphous phase, it is also preferred that this raw material contains SiS 2 , B 2 S 3 , GeS 2 , Al 2 S 3 and other sulfides. Since it is easy to form an amorphous phase, when obtaining an amorphous by quenching, even if the cooling rate is reduced, an amorphous sulfide-based solid electrolyte can be obtained, and the equipment load can be reduced.

[0062] In addition, from the viewpoints of imparting moisture resistance to the sulfide-based solid electrolyte and the like, it is also preferred to contain SiO 2 , B 2 O 3 , GeO 2 , Al 2 O 3 , P 2 O 5 , ZrO 2 , Ta 2 O 5 , TiO 2 , La 2 O 3 and other oxides. These compounds can be used alone or in combination of two or more.

[0063] It should be noted that the above sulfides and oxides can be included in this raw material, or can be added separately when the raw material is heated and melted. In addition, the addition amount of the above sulfides and oxides is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, relative to the total amount of the raw material. In addition, the addition amount is preferably 50% by mass or less, more preferably 40% by mass or less.

[0064] In addition, this raw material can also contain the compounds serving as crystal nuclei described later.

[0065] This manufacturing method is particularly applicable to the case where the raw material contains compounds with high volatility. Examples of the compounds with high volatility include LiI, B 2 S 3 , S, Se, Sb 2 S 3 and P 2 S 5 etc.

[0066] (Manufacturing apparatus for sulfide-based solid electrolyte)

[0067] Here, a manufacturing apparatus for a sulfide-based solid electrolyte (hereinafter, also referred to as this manufacturing apparatus) used in the present invention will be described with reference to Figure 2 FIG. Figure 2 is a cross-sectional schematic view showing an example of a manufacturing apparatus for a sulfide-based solid electrolyte according to an embodiment of the present invention.

[0068] In Figure 2 , the manufacturing apparatus 1 for a sulfide-based solid electrolyte is characterized by having: a furnace body 10 for heating and melting a sulfide-based solid electrolyte raw material, and a flow path 12 for discharging the melt 11 obtained by the above heating and melting to the outside of the furnace body; the flow path 12 is provided with a heating portion 13 for heating the flow path 12, and a cooling portion 14 for cooling the melt 11 near the downstream end portion of the flow path 12.

[0069] In this manufacturing apparatus 1, it is preferable to continuously supply the sulfide-based solid electrolyte raw material into the furnace body 10 and discharge the melt 11 described below to the outside of the furnace body 10. When this continuous manufacturing method is adopted, the effects of the present invention are further improved. The continuous supply of the sulfide-based solid electrolyte raw material into the furnace body 10 is preferably quantitative supply. As the method of quantitative supply, there is no particular limitation, and for example, methods such as using a screw feeder, a table feeder, and pneumatic conveying can be cited.

[0070] (Heating and melting)

[0071] The heating and melting of the sulfide-based solid electrolyte raw material is preferably carried out in an atmosphere containing sulfur. By heating and melting the raw material in an atmosphere containing sulfur, sulfur is introduced into the melt. As a result, the volatilization of sulfur during heating can be suppressed, so the composition of the obtained sulfide-based solid electrolyte can be appropriately controlled. The gas containing sulfur is, for example, a compound containing sulfur such as sulfur gas, hydrogen sulfide gas, carbon disulfide gas, or a gas of sulfur.

[0072] The gas atmosphere containing sulfur element can be obtained by supplying a sulfur source to a sulfide-based solid electrolyte raw material or a melt, and heating the sulfur source to generate a gas containing sulfur element. By supplying a sulfur source to the sulfide-based solid electrolyte raw material, the sulfur source is also heated when the sulfide-based solid electrolyte raw material is heated and melted, so that the sulfide-based solid electrolyte raw material can be heated and melted in the generated gas atmosphere containing sulfur element. In addition, by supplying a sulfur source to the melt, the sulfide-based solid electrolyte raw material can also be heated and melted in the generated gas atmosphere containing sulfur element.

[0073] In the above embodiment, the sulfur source is not particularly limited as long as it is elemental sulfur or a sulfur compound, and examples thereof include 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 S, etc.), polysulfides such as lithium polysulfide and sodium polysulfide, polysulfides, rubber vulcanized with sulfur, etc. As the sulfur source, sulfur powder is preferably used.

[0074] Alternatively, the sulfur-containing gas atmosphere may be obtained by introducing sulfur vapor obtained in advance into the furnace body. For example, sulfur may be heated at 200 to 450°C to generate sulfur vapor, and then N 2 Inert gases such as nitrogen, argon, and helium are delivered into the furnace as carrier gases to obtain an atmosphere containing sulfur.

[0075] The temperature for heating and melting is not particularly limited. From the perspective of homogenizing the melt in a short time, it is preferably 600 °C or higher, more preferably 630 °C or higher, further preferably 650 °C or higher, and particularly preferably 700 °C or higher. Additionally, from the perspective of suppressing deterioration, decomposition, etc. of the components in the melt due to heating, the temperature for heating and melting is preferably 1000 °C or lower, more preferably 950 °C or lower, further preferably 900 °C or lower, further preferably 800 °C or lower, and particularly preferably 750 °C or lower. Moreover, the temperature for heating and melting is preferably 600 °C to 900 °C, more preferably 700 °C to 900 °C, and further preferably 700 °C to 750 °C. When heating to the above temperatures, it can be heated to the above temperatures, for example, by heating units ( Figure 2 the symbol 17 in

[0076] The time for heating and melting to obtain the melt is not particularly limited. For example, it can be 0.5 hours or more, 1 hour or more, or 2 hours or more. Additionally, for the time of heating and melting, when the deterioration and decomposition of the components in the melt due to heating are within an allowable range, the time of heating and melting can be longer. As an actual range, it is preferably 100 hours or less, more preferably 50 hours or less, and further preferably 25 hours or less.

[0077] The pressure during heating and melting is not particularly limited. For example, normal pressure or slightly reduced pressure is preferred, and normal pressure is more preferred.

[0078] During heating and melting, from the perspective of preventing side reactions with water vapor, oxygen, etc., the dew point in the furnace is preferably -20 °C or lower, and the lower limit is not particularly limited and is usually -80 °C or higher. Additionally, the oxygen concentration is preferably 1000 volume ppm or less.

[0079] (Discharge of the melt outside the furnace body)

[0080] Next, the obtained melt 11 is discharged outside the furnace body 10 through Figure 2 the heated flow path 12 shown.

[0081] The flow path 12 can continuously discharge the melt 11 from the furnace body 10 and preferably has a throttle portion capable of adjusting the flow rate and flow velocity of the melt 11. That is, the flow path 12 preferably has a throttle portion. Additionally, as the throttle portion, as Figure 2As shown, it is possible to adjust the discharge amount and discharge speed of the melt 11, and further preferably, the nozzle shape that inhibits the instantaneous large amount of discharge of the melt 11 from the furnace body 10. That is, the shape of the throttle portion is preferably a nozzle shape.

[0082] Since the flow path 12 has a throttle portion, the following effects are achieved:

[0083] When heating the discharge outlet in a state without a throttle portion, the overall heat capacity is large and a large amount of energy is required. However, since the flow path 12 has a throttle portion, the heat capacity can be locally reduced and not much energy is needed; due to local heating, the temperature of the melt 11 is inhibited from rising excessively, and it is easy to maintain the crystal structure of the obtained sulfide-based solid electrolyte; the heating portion is simplified for heating the flow path 12 having a throttle portion; by arranging the flow path 12 having a throttle portion near the cooling portion, the high-temperature melt 11 is rapidly cooled, and the generation of gas from the melt 11 is inhibited; thus, the adhesion of condensates from the gas is inhibited, and stable operation of the device can be achieved; since local temperature control can be realized, if the operation of the heating portion is stopped, the melt 11 solidifies and the outflow operation can be stopped.

[0084] The flow rate of the melt 11 passing through the flow path 12 can be determined by considering the scale of this manufacturing device, the type of the desired sulfide-based solid electrolyte, etc., and there is no particular limitation. For example, it can be 4.0 kg / min or less. By setting the flow rate of the melt 11 passing through the flow path 12 to 4.0 kg / min or less, the heat during heating the flow path 12 is inhibited. For example, in the case where the nozzle shape is adopted as the throttle portion of the flow path 12, the above flow rate can be adjusted by adjusting the size of the cross-section of the nozzle, which is orthogonal to the flow direction of the melt 11.

[0085] The flow path 12 is heated by a heating portion 13 provided, for example, along the flow direction of the flow path. Through this heating, it is possible to inhibit the melt 11 from solidifying before reaching the cooling portion described below, and prevent the adhesion of condensates from the gas of the melt 11 to the flow path 12 or other peripheral equipment. As the heating portion 13, there is no particular limitation. For example, a Kanthal heater, an SiC heater, a carbon heater, etc., which are heaters that heat an object by passing an electric current through a heating material, a halogen heater, etc., which are heaters that perform radiant heating, a high-frequency induction heating device, an electric heating device, etc. can be appropriately used, and the temperature of the melt 11 flowing through the flow path 12 can be maintained at a desired temperature.

[0086] The heating temperature of the flow path 12 can be appropriately determined according to the type of the sulfide-based solid electrolyte raw material, etc., and is preferably 500 °C or higher, more preferably 525 °C to 1000 °C, and further preferably 550 °C to 950 °C.

[0087] (Cooling of the melt)

[0088] Next, the melt 11 passing through the flow path 12 reaches a cooling unit 14 provided near the terminal end portion in the downstream direction of the flow path, where the melt 11 is cooled.

[0089] Cooling can be performed using a known method, and the method is not particularly limited. As a more specific method of cooling, for example, there can be cited a method of cooling the molten metal by flowing out onto a plate-like body of metal, carbon or ceramic that is internally water-cooled; a method represented by a double-roll method in which the molten metal is poured into a narrow gap that is water-cooled for rapid cooling; a single-roll method in which the molten metal is sprayed onto a high-speed rotating roller for rapid cooling; a gas atomization method in which the molten metal is poured into a gas sprayer for rapid cooling; a disk atomization method in which the molten metal is poured onto a rotating disk, etc. In an embodiment of the present invention, cooling is preferably performed using a double-roll method. In addition, in other embodiments, cooling is preferably performed using a gas atomization method.

[0090] When the molten metal is poured onto a plate-like body for cooling, the thickness of the molten metal and the obtained solid after pouring out is preferably thin from the viewpoint of improving cooling efficiency. Specifically, the thickness is preferably 10 mm or less, and more preferably 5 mm or less. The lower limit of the thickness is not particularly limited, and may be 0.01 mm or more, or 0.02 mm or more.

[0091] When the material is poured into a narrow gap and formed thinly, the cooling efficiency is excellent, and a flaky molded body, a fibrous solid, a powdery solid, etc. can be obtained. The obtained solid is crushed into a size that is easy to handle, etc., and any shape can be obtained. Among them, it is easier to recycle with a block solid, so it is preferred. The block also includes the case of a plate, a flaky or a fibrous shape.

[0092] From the viewpoint of maintaining the composition obtained by heating and melting, the cooling rate is preferably 0.01°C / sec or more, more preferably 0.05°C / sec or more, and even more preferably 0.1°C / sec or more. In addition, the upper limit of the cooling rate is not particularly limited, but it is generally believed that the cooling rate of the twin-roll method with a fast quenching rate is 10 7 ℃ / second or less.

[0093] Here, in the case of a sulfide-based solid electrolyte that is intended to obtain an amorphous solid, it is preferred to quench the melt obtained by heating and melting to obtain a solid. Specifically, the cooling rate during quenching is preferably 10°C / sec or more, more preferably 100°C / sec or more, further preferably 500°C / sec or more, and further preferably 700°C / sec or more. In addition, the upper limit of the cooling rate is not particularly limited, and it is generally believed that the cooling rate of the twin-roll method with a fast quenching rate is 10 7 ℃ / second or less.

[0094] On the other hand, by performing slow cooling during cooling, at least a part of the solid can be crystallized to obtain a sulfide-based solid electrolyte having a specific crystal structure or a sulfide-based solid electrolyte composed of a crystalline phase and an amorphous phase. The cooling rate during slow cooling is preferably 0.01 °C / second or more, more preferably 0.05 °C / second or more. In addition, the cooling rate is preferably 500 °C / second or less, more preferably 450 °C / second or less. The cooling rate can be 10 °C / second or less, or can be 5 °C / second or less. It should be noted that the cooling rate can be appropriately adjusted according to the crystallization conditions.

[0095] Here, the crystal contained in the sulfide-based solid electrolyte is preferably an ion-conductive crystal. Specifically, the ion-conductive crystal means that the lithium ion conductivity is greater than 10 -4 S / cm, more preferably greater than 10 －3 S / cm crystal.

[0096] When the solid obtained after cooling is desired to be a sulfide-based solid electrolyte containing a crystalline phase, it is preferable to contain a compound that becomes a crystal nucleus in the melt obtained during heat melting. Thereby, crystals are likely to precipitate during cooling. The method of making the melt contain a compound that becomes a crystal nucleus is not particularly limited. For example, methods such as adding a compound that becomes a crystal nucleus to the raw material, the heat-treated raw material, and adding a compound that becomes a crystal nucleus to the melt during heat melting can be cited.

[0097] Examples of the compound that becomes a crystal nucleus include oxides, oxynitrides, nitrides, carbides, other chalcogenides, halides, etc. The compound that becomes a crystal nucleus is preferably a compound having a certain degree of compatibility with the melt. It should be noted that a compound that is completely incompatible with the melt cannot become a crystal nucleus.

[0098] When the solid obtained after cooling is desired to be a sulfide-based solid electrolyte containing a crystalline phase, the content of the compound that becomes a crystal nucleus in the melt is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 1% by mass or more. On the other hand, from the viewpoint of suppressing the decrease in lithium ion conductivity, the content of the compound that becomes a crystal nucleus in the melt is preferably 20% by mass or less, more preferably 10% by mass or less.

[0099] When the solid obtained after cooling is desired to be an amorphous sulfide-based solid electrolyte, it is preferable that the melt does not contain a compound that becomes a crystal nucleus or its content is below a specified amount. Specifically, the content of the compound that becomes a crystal nucleus in the melt is preferably 1% by mass or less, more preferably 0.1% by mass or less. The content of the compound that becomes a crystal nucleus in the melt can also be less than 0.01% by mass.

[0100] This manufacturing method may further include a step of performing known post-treatment or the like on the sulfide-based solid electrolyte obtained by cooling the molten liquid. As the post-treatment step, for example, the following steps can be cited: from the viewpoint of obtaining desired properties and the like, a step of further heat-treating the sulfide-based solid electrolyte; from the viewpoint of obtaining a desired shape and the like, a step of performing a pulverization treatment and the like.

[0101] An example of the above cooling using the twin-roll method will be described. The twin-roll method is well-known. For example, Figure 2 As shown, the molten liquid 11 supplied from the flow path 12 is introduced between the twin rolls composed of water-cooled rolls 142 and 144 serving as the cooling unit 14, and after solidifying between the rolls 142 and 144, it is discharged in the form of a plate, a thin sheet, or the like.

[0102] In addition, the installation positions of the rolls 142 and 144 are near the terminal portion in the downstream direction of the flow path 12. Specifically, as the distance from the terminal portion in the downstream direction, it is preferably 5 mm to 500 mm, and more preferably 10 mm to 300 mm.

[0103] The sulfide-based solid electrolyte raw material discharged in the form of a plate after solidifying between the rolls 142 and 144 can be powdered as needed.

[0104] Next, the cooling of the molten liquid using the gas atomization method will be described.

[0105] The gas atomization method is well-known. For example, Figure 3 the manufacturing apparatus 2 shown, Figure 2 the twin rolls composed of the rolls 142 and 144 are replaced by a gas atomization device 15. The preparation conditions of the molten liquid 11 are the same as Figure 2 those. In the gas atomization method, as Figure 3 shown, while discharging the obtained molten liquid 11 from the furnace body 10, a spray gas is used to cool and solidify the molten liquid 11 to obtain a sulfide-based solid electrolyte. The obtained sulfide-based solid electrolyte becomes powdery.

[0106] As a method of gas atomization, for example, by spraying a gas onto the melt 11 discharged from the flow path 12 using a gas atomization device 15, the melt 11 is cooled, solidified, and pulverized. Since the melt 11 is cooled and solidified by spraying a gas, the melt 11 does not come into contact with other components during cooling, suppressing contamination by impurities and obtaining a sulfide-based solid electrolyte with excellent battery performance. In addition, when the gas atomization method is used, since surface reactions at component contact parts do not occur, there are no restrictions on the components used, and the degree of freedom in component selection is increased. Further, since the method of using a spray gas can perform pulverization while cooling and solidifying the melt, there is no need to go through an additional pulverization process. Furthermore, by cooling with a spray gas, fine powders with a small diameter can be obtained, enabling rapid cooling. Therefore, not only is the cooling time shortened and the production volume increased, but the quality also improves along with the rapid cooling. In this way, by the gas atomization method, a sulfide-based solid electrolyte with good quality can be simply manufactured without going through complex processes.

[0107] The gas atomization device 15 is appropriately arranged in such a way as to spray a gas onto the melt 11 discharged from the flow path 12.

[0108] As the above-mentioned gas, an inert gas such as nitrogen or argon is preferably used. From the viewpoints of reducing the powder particle size and the heat capacity per unit powder, the spray pressure of the gas is preferably 0.2 MPa or more, more preferably 0.5 MPa or more, and further preferably 0.8 MPa or more. In addition, there is no specific limitation on the upper limit of the gas spray pressure. From the viewpoints of continuous operation stability and realistic gas spray cost, it is preferably 10 MPa or less, more preferably 9.5 MPa or less, and further preferably 9 MPa or less. In addition, the spray pressure of the gas is preferably 0.2 MPa to 10 MPa, more preferably 0.5 MPa to 9.5 MPa, and further preferably 0.8 MPa to 9 MPa. The gas velocity is not particularly limited and can be, for example, 300 m / s or more, 350 m / s or more, or 400 m / s or more. The gas temperature is not particularly limited and is, for example, 100 °C or less, preferably room temperature.

[0109] The oxygen concentration of the above-mentioned gas can be adjusted as needed. The oxygen concentration of the gas is preferably less than 100 volume ppm, more preferably less than 10 volume ppm, and further preferably less than 1 volume ppm. In addition, the dew point of the gas, measured at atmospheric pressure, is preferably less than -30 °C, more preferably less than -40 °C, and further preferably less than -50 °C.

[0110] The spraying of gas into the melt is preferably carried out in a sealed chamber (not shown) without exposing it to the atmosphere, and the obtained sulfide-based solid electrolyte is recovered. Thereby, it is possible to prevent the quality of the solid electrolyte from deteriorating due to reactions with components in the atmosphere, particularly oxygen and moisture. Here, the sealed chamber refers to a chamber that is isolated from the atmosphere inside, such as a vacuum chamber or a chamber that seals gas. The dew point inside the sealed chamber is preferably less than -30°C, more preferably less than -40°C, and further preferably less than -50°C. By making the dew point inside the sealed chamber less than -30°C, the state of the interface can be normally maintained, and the deterioration of battery performance can be prevented. In addition, the lower limit of the dew point inside the sealed chamber is only required to be within the actual range and is not particularly limited. For example, it can be -80°C or higher. From the viewpoint of maintaining the quality of the solid electrolyte and preventing the deterioration of battery performance, the oxygen concentration inside the sealed chamber is preferably less than 100 volume ppm, more preferably less than 10 volume ppm, and further preferably less than 1 volume ppm. The lower limit of the oxygen concentration is not specifically limited, and from the viewpoint of actual operating costs, it can be 0.01 volume ppm or higher.

[0111] As described above, both the twin-roll method and the gas atomization method are methods for rapidly cooling the melt, but from the viewpoint of suppressing gas generation, it is preferable to sufficiently heat the melt immediately before rapid cooling.

[0112] In addition, it is preferable that the installation position of the heating part 13 of the flow path 12 is at a certain distance from the furnace body 10 to suppress the heat transfer generated by the heating part 13 to the furnace body 10.

[0113] On the other hand, in this manufacturing apparatus, it is preferable to provide a heat insulation layer between the furnace body 10 and the flow path 12. Or it is preferable to provide a heat insulation layer between the furnace body 10 and the heating part 13. Figure 4 It is a cross-sectional schematic view showing another example of a manufacturing apparatus for a sulfide-based solid electrolyte according to an embodiment of the present invention in which such a heat insulation layer is provided.

[0114] According to Figure 4 , in Figure 2 In the configuration of the manufacturing apparatus 1, a plurality of heat insulation layers 18 are provided between the furnace body 10 and the flow path 12 (heating part 13). Due to the presence of the heat insulation layer 18, it is possible to suppress the heat transfer generated by the heating of the flow path 12 to the furnace body 10, and it is possible to maintain the heating and melting conditions carried out in the furnace body 10 at the desired setting, and the quality of the obtained sulfide-based solid electrolyte is good.

[0115] There is no particular limitation on the material of the heat insulation layer 18. For example, ceramic fiber boards, carbon fiber heat insulation materials, bricks, calcium silicate materials, rock slab materials, etc. can be cited. The heat insulation layer 18 is preferably disposed on substantially the entire bottom of the furnace body 10. In addition, the thickness of the heat insulation layer 18 in the direction parallel to the flow direction of the melt 11 in the flow path 12 is, for example, preferably 10 mm to 500 mm, and more preferably 20 mm to 250 mm.

[0116] It should be noted that the heat insulation layer 18 can also be similarly provided in the manufacturing apparatus 2 Figure 3 shown.

[0117] (Reheating treatment)

[0118] When the solid obtained by cooling the melt in this manufacturing method is an amorphous sulfide-based solid electrolyte or a sulfide-based solid electrolyte containing an amorphous phase, the manufacturing method further includes a step of reheating the solid electrolyte. In addition, by reheating a sulfide-based solid electrolyte containing crystals of a sulfide-based solid electrolyte, the ions in the crystal structure can be rearranged again to improve the lithium ion conductivity. It should be noted that the reheating treatment refers to heating the powder obtained by cooling for at least one of crystallization and rearrangement of ions in the crystal structure.

[0119] (Crushing)

[0120] The obtained sulfide-based solid electrolyte can be further pulverized to achieve further micronization. As a pulverization method, for example, a wet pulverization method can be cited. In the case of the wet pulverization method, the type of solvent used is not particularly limited. Since the sulfide-based solid electrolyte has the property of being easily deteriorated by reacting with moisture, it is preferable to use a non-aqueous organic solvent. The type of non-aqueous organic solvent is not particularly limited, and examples thereof include hydrocarbon solvents, organic solvents containing hydroxyl groups, organic solvents containing ether groups, organic solvents containing carbonyl groups, organic solvents containing ester groups, organic solvents containing amino groups, organic solvents containing formyl groups, organic solvents containing carboxyl groups, organic solvents containing amide groups, organic solvents containing benzene rings, organic solvents containing mercapto groups, organic solvents containing thioether groups, organic solvents containing thioester groups, organic solvents containing disulfide groups, and halogenated alkanes. As hydrocarbon solvents, for example, cyclohexane, heptane, octane, and toluene can be cited. From the viewpoint of low saturated moisture concentration, cyclohexane, heptane, and octane are preferable. In addition, from the viewpoint of adjusting the moisture concentration, a mixed solvent obtained by mixing these hydrocarbon solvents with toluene and dibutyl ether is preferable. From the viewpoint of preventing the sulfide-based solid electrolyte from reacting with water during the pulverization of the sulfide-based solid electrolyte and reducing the lithium ion conductivity, the lower the moisture concentration of the above non-aqueous organic solvent, the more preferable. The moisture concentration of the above non-aqueous organic solvent can be, for example, 170 mass ppm or less, 150 mass ppm or less, 120 mass ppm or less, or 100 mass ppm or less.

[0121] The wet pulverization method can be carried out, for example, using a pulverizer such as a ball mill, a planetary ball mill, or a bead mill. In the wet pulverization, in addition to the above solvent, an ether compound, an ester compound, or a nitrile compound can be added as an additive (dispersant).

[0122] In the sulfide-based solid electrolyte obtained via wet pulverization, when the solvent and the additive remain, a drying process can be carried out. As drying conditions, for example, the temperature can be 100°C to 200°C. The drying time is not particularly limited and can be, for example, 10 minutes or more and 24 hours or less. In addition, the drying process can be carried out under reduced pressure. For example, the absolute pressure can be 50 kPa or less. The drying process can be carried out using a hot plate, a drying furnace, an electric furnace, etc.

[0123] This manufacturing method can be used to manufacture various solid electrolytes, and specific examples thereof are shown in Table 1 and Table 2. That is, by melting and synthesizing the raw materials described in the raw material column of Table 1 or Table 2, the solid electrolytes described in the representative composition column can be manufactured. It should be noted that the values shown in Table 1 and Table 2 are only examples, and the scope of application of the present invention is not limited to these.

[0124]

[0125]

[0126] (sulfide-based solid electrolyte)

[0127] As the sulfide-based solid electrolyte obtained by this manufacturing method, a sulfide-based solid electrolyte containing a lithium element can be cited. As the sulfide-based solid electrolyte obtained by this manufacturing method, for example, Li 10 GeP 2 S 12 and other sulfide-based solid electrolytes having an LGPS-type crystal structure; Li 6 PS 5 Cl, Li 5.4 PS 4.4 Cl 1.6 and Li 5.4 PS 4.4 Cl 0.8 Br 0.8 and other sulfide-based solid electrolytes having an argyrodite-type crystal structure; microcrystalline glass of the Li-P-S-Ha system (Ha is at least one element selected from halogen elements); and LPS microcrystalline glass such as Li 7 P 3 S 11 and the like.

[0128] In addition, as the sulfide-based solid electrolyte obtained by this manufacturing method, the substances described in Table 1 and Table 2 above can be cited.

[0129] The sulfide-based solid electrolyte can be an amorphous sulfide-based solid electrolyte according to its purpose, a sulfide-based solid electrolyte having a specific crystal structure, or a sulfide-based solid electrolyte containing a crystalline phase and an amorphous phase. From the viewpoint of lithium ion conductivity, the crystalline phase is more preferably an argyrodite-type crystalline phase.

[0130] As the sulfide-based solid electrolyte having excellent lithium ion conductivity, a sulfide-based solid electrolyte having elements of Li-P-S-Ha is preferred, and a crystalline phase is more preferred. In addition, for this halogen element, the halogen element is preferably derived from one or more selected from lithium chloride, lithium bromide, and lithium iodide.

[0131] When the lithium ion conductivity of the sulfide-based solid electrolyte is used in a lithium ion secondary battery, from the viewpoint of making the battery characteristics good, it is preferably 1.0×10 -4 S / cm or more, more preferably 5.0×10 -4 S / cm or more, further preferably 1.0×10 -3 S / cm or more, and particularly preferably 5.0×10 -3Above S / cm. The above-mentioned lithium ion conductivity is measured using an alternating current impedance measuring device (for example, VSP, a potentiostat / galvanostat manufactured by Bio-LLogic Sciences Instruments Co., Ltd.) under the measurement conditions of measurement frequency: 100 Hz to 1 MHz, measurement voltage: 100 mV, and measurement temperature: 25°C.

[0132] The obtained sulfide-based solid electrolyte can be identified by analyzing the crystal structure through X-ray diffraction (XRD) measurement and analyzing the elemental composition by various methods such as ICP emission spectrometry, atomic absorption spectrometry, and ion chromatography. For example, P and S can be measured by ICP emission spectrometry, Li can be measured by atomic absorption spectrometry, and Ha can be measured by ion chromatography.

[0133] In addition, by performing Raman spectroscopy measurement, the homogeneity of the composition of the sulfide-based solid electrolyte can be evaluated. Specifically, Raman spectroscopy measurement is performed on the sample obtained from the obtained sulfide-based solid electrolyte at two or more arbitrary points. It should be noted that from the viewpoint of improving the accuracy of evaluation, the number of measurement points is preferably 8 or more, and more preferably 10 or more. As the preferred conditions for Raman spectroscopy measurement when evaluating the homogeneity of the composition of the sulfide-based solid electrolyte, for example, the spot diameter can be set to 3 μm and the number of measurement points can be set to 10. By setting the spot diameter to 3 μm, the analysis region in Raman spectroscopy measurement becomes a size suitable for evaluating the homogeneity of the composition of the sulfide-based solid electrolyte at the microscopic level.

[0134] It can be considered that the smaller the deviation of the peak wave number (peak position) of the structure of the sulfide-based solid electrolyte such as PS 4 3－ in each measurement result, the more homogeneous the composition of the sulfide-based solid electrolyte. Alternatively, it can be considered that the smaller the deviation of the full width at half maximum of the peak of the structure of the sulfide-based solid electrolyte, the more homogeneous the composition of the sulfide-based solid electrolyte.

[0135] Although it also depends on the composition of the obtained sulfide-based solid electrolyte, it is preferable to identify the peak from the P-S bond as the peak of the structure of the sulfide-based solid electrolyte. The position of the peak from the P-S bond varies depending on the composition system, and typically it is included between 350 cm -1 and 500 cm -1 . Hereinafter, in this specification, the deviation of the peak position and the deviation of the full width at half maximum of the peak refer to the values confirmed for the peak with the strongest intensity among the peaks from the P-S bond.

[0136] The deviation of the peak position can be evaluated as follows. That is, the standard deviation of the peak position of each measurement point obtained by Raman spectroscopy measurement is calculated. When it is recorded as (average peak position) ± (standard deviation), the value of the standard deviation is preferably 2 cm -1 or less, more preferably 1 cm -1 or less, and still more preferably 0.5 cm -1 or less. It should be noted that the peak position here refers to the position of the peak top. For example, regarding the sulfide-based solid electrolyte obtained by this manufacturing method, when Raman spectroscopy measurement is performed with a spot diameter of 3 μm and the number of measurement points is 10, the standard deviation of the peak position of the peak from the P-S bond at 350 cm -1 to 500 cm -1 for each measurement point is preferably 2 cm -1 or less, more preferably 1 cm -1 or less, and still more preferably 0.5 cm -1 or less.

[0137] The deviation of the full width at half maximum (FWHM) of the peak can be evaluated as follows. That is, the standard deviation of the FWHM of the peak of each measurement point obtained by Raman spectroscopy measurement is calculated using a method of obtaining the FWHM of each peak and calculating the standard deviation of this value. When it is recorded as (average FWHM of the peak) ± (standard deviation), the value of the standard deviation is preferably 2 cm -1 or less, more preferably 1.5 cm -1 or less. It should be noted that the FWHM of the peak refers to the width at which the peak intensity of the peak from the P-S bond intersects with half of the peak intensity when the Raman spectrum is plotted. For example, regarding the sulfide-based solid electrolyte obtained by this manufacturing method, when spectroscopy measurement is performed with a spot diameter of 3 μm and the number of measurement points is 10, the standard deviation of the FWHM of the peak from the P-S bond at 350 cm -1 to 500 cm -1 for each measurement point is preferably 2 cm -1 or less, more preferably 1.5 cm -1 or less.

[0138] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above embodiments, and can be appropriately modified and improved. In addition, the materials, shapes, dimensions, numbers, and arrangement positions of the respective constituent elements in the above embodiments can be arbitrary as long as the present invention can be realized, and there is no limitation.

[0139] As described above, the present specification discloses the following matters.

[0140] [1] A method for manufacturing a sulfide-based solid electrolyte, comprising supplying a sulfide-based solid electrolyte raw material into a furnace body, heating and melting the sulfide-based solid electrolyte raw material, and discharging the obtained melt through a heated flow path to the outside of the furnace body and cooling it.

[0141] [2] The method for manufacturing a sulfide-based solid electrolyte according to [1] above, wherein the flow path has a throttle portion.

[0142] [3] The method for manufacturing a sulfide-based solid electrolyte according to [2] above, wherein the shape of the throttle portion is a nozzle shape.

[0143] [4] The method for manufacturing a sulfide-based solid electrolyte according to any one of [1] to [3] above, wherein a heat insulation layer is provided between the furnace body and the flow path.

[0144] [5] The method for manufacturing a sulfide-based solid electrolyte according to any one of [1] to [4] above, wherein the heating temperature of the flow path is 500 °C or higher.

[0145] [6] The method for manufacturing a sulfide-based solid electrolyte according to any one of [1] to [5] above, wherein the supply of the sulfide-based solid electrolyte raw material into the furnace body and the discharge of the melt to the outside of the furnace body are continuously performed.

[0146] [7] The method for manufacturing a sulfide-based solid electrolyte according to any one of [1] to [6] above, wherein the cooling is performed by a twin-roll method.

[0147] [8] The method for manufacturing a sulfide-based solid electrolyte according to any one of [1] to [6] above, wherein the cooling is performed by a gas atomization method.

[0148] [9] A manufacturing apparatus for a sulfide-based solid electrolyte, comprising:

[0149] A furnace body for heating and melting a sulfide-based solid electrolyte raw material, and

[0150] A flow path for discharging the melt obtained by the above heating and melting to the outside of the furnace body;

[0151] The above flow path is provided with a heating portion for heating the flow path, and

[0152] A cooling portion for cooling the melt is provided near the terminal portion in the downstream direction of the above flow path.

[0153]

[10] The manufacturing apparatus for a sulfide-based solid electrolyte according to [9] above, wherein the flow path has a throttle portion.

[0154]

[11] The manufacturing apparatus for a sulfide-based solid electrolyte according to

[10] above, wherein the shape of the throttle portion is a nozzle shape.

[0155]

[12] The manufacturing apparatus for a sulfide-based solid electrolyte according to any one of [9] to

[11] above, wherein a heat insulating layer is provided between the furnace body and the flow path.

[0156] Examples

[0157] Examples are given below to specifically illustrate the present invention, but the present invention is not limited thereto. Examples 1 to 3 are examples, and Example 4 is a comparative example.

[0158] Example 1

[0159] According to Figure 2 the specifications of the manufacturing apparatus 1 shown, tests were conducted.

[0160] As raw materials, Li 2 S (manufactured by Sigma, purity 99.98%), P 2 S 5 (manufactured by Sigma, purity 99%) and LiCl (manufactured by Sigma, purity 99.99%) were respectively blended into powders in a ratio of 1.9:0.5:1.6 (molar ratio) to obtain raw material powders.

[0161] On the other hand, a carbon crucible (furnace body 10) with an internal volume of about 1 L was prepared, and a heater (heating portion 17 of the furnace body) was arranged around it. Nitrogen purge was carried out to make the dew point inside the crucible -60°C and the oxygen concentration less than 100 ppm.

[0162] A metering feeder (MicronFeeder manufactured by Aishin Nano Technologies) was arranged at the upper part inside the crucible and set to supply the above raw material powders into the crucible. It should be noted that the hopper tank installed on the metering feeder was also purged with nitrogen and set so that the dew point inside was -60°C and the oxygen concentration was less than 100 ppm.

[0163] Next, the above raw material powders were put into the hopper tank, and 500 g of the above raw material powders were supplied into the crucible. After the supply, the inside of the crucible was heated up, and the raw material powders were heated and melted to obtain a melt at 700°C.

[0164] After obtaining the melt, using the above metering feeder, the above raw material powders were continuously supplied into the crucible at a ratio of 0.1 g / second. It should be noted that at this time, sulfur powder was added in an amount of 5% by mass relative to the melt.

[0165] On the other hand, a flow path (flow path 12) having a nozzle-shaped throttle portion with a heater (heating portion 13) provided around it is provided at the bottom of the crucible, and the internal temperature of the flow path is heated to 600°C.

[0166] After the heating of the flow path is completed, the above-mentioned melt is discharged from the inside of the crucible through the flow path (discharge speed = 0.1 g / second), and is rapidly cooled using water-cooled double rollers (rollers 142, 144) provided 130 mm below the terminal portion of the flow path to obtain a sulfide-based solid electrolyte.

[0167] When 2 kg of the sulfide-based solid electrolyte is obtained, the metering feeder is stopped, and the operation of the heater of the flow path is also stopped.

[0168] No adhesions of gas from the melt were observed around the flow path having a nozzle-shaped throttle portion.

[0169] Example 2

[0170] According to Figure 3 the specifications of the manufacturing apparatus 2 shown, tests are conducted.

[0171] All conditions are the same as in Example 1, but the gas atomization method is used instead of quenching using double rollers.

[0172] When the melt is discharged from the inside of the crucible through the flow path, the melt is rapidly cooled and solidified and pulverized under the conditions of gas type: nitrogen, gas temperature: 20°C, and gas spray pressure: 0.9 MPa to obtain a sulfide-based solid electrolyte.

[0173] When 2 kg of the sulfide-based solid electrolyte is obtained, the metering feeder is stopped, and the operation of the heater of the flow path is also stopped.

[0174] No adhesions of gas from the melt were observed around the flow path having a nozzle-shaped throttle portion.

[0175] Example 3

[0176] According to Figure 4 the specifications of the manufacturing apparatus 3 shown, tests are conducted.

[0177] All conditions are the same as in Example 1, but a heat insulating layer (heat insulating layer 18) is provided between the bottom of the crucible and the flow path. As the material of the heat insulating layer, a ceramic fiber board is used. In addition, the heat insulating layer is disposed on substantially the entire bottom of the crucible, and its thickness is set to 60 mm.

[0178] When 2 kg of the sulfide-based solid electrolyte is obtained, the metering feeder is stopped, and the operation of the heater of the flow path is also stopped.

[0179] No adhesions of gas from the melt were observed around the flow path having a nozzle-shaped throttle portion.

[0180] Example 4

[0181] According to Figure 5 the specifications of the manufacturing apparatus 4 shown, conduct tests.

[0182] That is, the conditions are the same as in Example 1. In the manufacturing apparatus 4, a direct discharge port is provided at the bottom of the crucible (furnace body 10), and the molten liquid is introduced into the twin rolls without heating the discharge port.

[0183] Stop the metering feeder when 2 kg of the sulfide-based solid electrolyte is obtained.

[0184] Adhesions of gas from the molten liquid are observed around the discharge port.

[0185] Although the present invention has been described in detail with reference to specific embodiments, various changes and modifications can be made without departing from the spirit and scope of the present invention, which will be apparent to those skilled in the art. This application is based on a Japanese patent application filed on November 2, 2022 (Japanese Patent Application No. 2022-176672), the content of which is incorporated herein by reference.

[0186] Symbol Explanation

[0187] 1, 2, 3, 4 Manufacturing apparatuses for sulfide-based solid electrolytes

[0188] 10 Furnace body

[0189] 11 Molten liquid

[0190] 12 Flow path

[0191] 13 (Heating part of the flow path)

[0192] 14 Cooling part

[0193] 142, 144 Rolls

[0194] 15 Gas atomization device

[0195] 17 (Heating part of the furnace body)

[0196] 18 Heat insulation layer

Claims

1. A method for manufacturing a sulfide-based solid electrolyte, comprising supplying a sulfide-based solid electrolyte raw material into a furnace body, heating and melting the sulfide-based solid electrolyte raw material, and discharging the obtained melt through a heated flow path to the outside of the furnace body for cooling.

2. The method for manufacturing a sulfide-based solid electrolyte according to claim 1, wherein, the flow path has a throttle portion.

3. The method for manufacturing a sulfide-based solid electrolyte according to claim 2, wherein, the shape of the throttle portion is a nozzle shape.

4. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, a heat insulating layer is provided between the furnace body and the flow path.

5. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, the heating temperature of the flow path is 500 °C or higher.

6. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, the supply of the sulfide-based solid electrolyte raw material into the furnace body and the discharge of the melt to the outside of the furnace body are continuously performed.

7. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, the cooling is performed by a twin-roll method.

8. The method for manufacturing a sulfide-based solid electrolyte according to claim 1 or 2, wherein, the cooling is performed by a gas atomization method.

9. A manufacturing apparatus for a sulfide-based solid electrolyte, comprising: a furnace body for heating and melting a sulfide-based solid electrolyte raw material, and a flow path for discharging the melt obtained by the heating and melting to the outside of the furnace body; the flow path is provided with a heating portion for heating the flow path, and a cooling portion for cooling the melt is provided near the terminal portion in the downstream direction of the flow path.

10. The manufacturing apparatus for a sulfide-based solid electrolyte according to claim 9, wherein, the flow path has a throttle portion.

11. The manufacturing apparatus for a sulfide-based solid electrolyte according to claim 10, wherein, the shape of the throttle portion is a nozzle shape.

12. The manufacturing apparatus for a sulfide-based solid electrolyte according to any one of claims 9 to 11, wherein, a heat insulating layer is provided between the furnace body and the flow path.

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