Method and device for producing sulfide solid electrolyte

Abstract

The present invention relates to a method for producing a sulfide-based solid electrolyte in which a raw material is heated and melted in a heating furnace provided with a sulfur supply unit, a partition unit provided inside the heating furnace, and one or more other structures capable of connecting the inside and the outside of the heating furnace, and in which the raw material is heated and melted to form a melt. A gap between the molten metal and the heating furnace is separated into a first space in which the sulfur supply unit is located and a second space in which another structure is located by the partition, and a sulfur excess atmosphere portion is formed by introducing a component containing elemental sulfur from the sulfur supply unit into the first space.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for producing 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.

[0003] In the past, liquid electrolytes were used in lithium-ion secondary batteries, but there were concerns about leakage, fire, etc., and the housing had to be enlarged for safety design. In addition, improvements were also desired in terms of short battery life and narrow operating temperature range.

[0004] On the other hand, all-solid-state lithium ion secondary batteries using a solid electrolyte as the electrolyte of the lithium ion secondary battery have attracted attention from the viewpoints of expected improvement in safety, high-speed charging and discharging, and miniaturization of the housing.

[0005] Solid electrolytes are roughly divided into sulfide-based solid electrolytes and oxide-based solid electrolytes. The sulfide ions constituting the sulfide-based solid electrolytes have a larger polarizability than the oxide ions constituting the oxide-based solid electrolytes, and show higher ion conductivity. As sulfide-based solid electrolytes, for example, sulfide-based solid electrolytes containing lithium, sulfur and phosphorus can be cited, and as methods for their manufacture, glass sealing tube method, mechanical grinding method, melting method, etc. are known.

[0006] Among them, the melting method is a method of synthesizing a sulfide-based solid electrolyte by heating and melting raw materials. In the melting method, sulfur components tend to volatilize during heating and melting, and composition control is difficult.

[0007] In contrast, Patent Document 1 describes that Li 2 S.SiS 2 After mixing in a predetermined stoichiometric ratio, sulfur powder or sulfur gas is added to the mixture, and the mixture is heated and melted in the presence of excess sulfur. In addition, it is described that according to the above method, it is possible to prevent the amount of sulfur in each constituent compound from being insufficient due to the generation of sulfur dioxide and hydrogen sulfide.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 6-115911 Summary of the invention

[0011] However, when heating and melting is performed in a gas atmosphere containing sulfur, if there are parts in the heating furnace where the temperature is easily lowered, such as the raw material input part and the pipe connection part, the sulfur contained in the gas will liquefy or solidify in the parts with lower temperatures and easily adhere to the parts. Moreover, if sulfur adheres, it will cause blockage in the device, so it may be difficult to continue production. Thus, when heating and melting is performed in a gas atmosphere containing sulfur, there is room for improvement in terms of productivity.

[0012] Therefore, an object of the present invention is to provide a method for producing a sulfide-based solid electrolyte and a production apparatus which are excellent in productivity and which can suppress the deposition of sulfur in the apparatus.

[0013] The present inventors have conducted intensive studies and have found that, in a method and apparatus for producing a sulfide-based solid electrolyte that is heated and melted in a gas atmosphere containing sulfur, the above-mentioned problems can be solved by separating a sulfur-excess atmosphere portion from a portion where sulfur adhesion is likely to occur in a heating furnace, thereby completing the present invention.

[0014] That is, the present invention relates to the following 1 to 11.

[0015] 1. A method for producing a sulfide-based solid electrolyte, comprising heating and melting a raw material in a heating furnace,

[0016] The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside.

[0017] The above raw materials are heated and melted to form a melt.

[0018] The partitioning portion separates the gap between the molten metal and the heating furnace into a first space where the sulfur supplying portion is located and a second space where the other structures are located.

[0019] A sulfur-excess atmosphere portion is formed by introducing a component containing sulfur element from the sulfur supply portion into the first space.

[0020] 2. The method for producing a sulfide-based solid electrolyte according to 1 above, wherein the other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

[0021] 3. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein the lowest temperature of the second space is 450° C. or lower.

[0022] 4. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, further comprising the step of: in a state where the sulfur-excess atmosphere section is provided in the heating furnace, communicating the interior of the heating furnace with the exterior through at least one of the other structures;

[0023] The second space includes another structure that allows the inside and outside of the heating furnace to communicate with each other.

[0024] 5. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, further comprising the steps of: heating a sulfur source at 200° C. to 450° C. outside the heating furnace to obtain a gas containing sulfur element;

[0025] The gas containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

[0026] 6. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein a solid containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

[0027] 7. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein the heating temperature in the heating and melting is 600°C to 900°C.

[0028] 8. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein the water dew point of the gas atmosphere separated from the first space in the heating furnace is lower than -30°C.

[0029] 9. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein the oxygen concentration of the gas atmosphere separated from the first space in the heating furnace is less than 100 ppm.

[0030] 10. A manufacturing apparatus for a sulfide-based solid electrolyte, comprising a heating furnace for heating and melting a raw material,

[0031] The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside.

[0032] The partition separates the melt formed by heating and melting the raw material in the heating furnace and the gap between the heating furnace into a first space where the sulfur supply unit is located and a second space where the other structures are located.

[0033] The sulfur supply unit forms a sulfur-excess atmosphere by introducing a component containing sulfur element into the first space.

[0034] 11. The apparatus for producing a sulfide-based solid electrolyte according to 10 above, wherein the other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

[0035] According to the present invention, it is possible to provide a method and an apparatus for producing a sulfide-based solid electrolyte which are excellent in productivity and which can suppress the deposition of sulfur in the apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flowchart illustrating a production method according to an embodiment of the present invention.

[0037] Figure 2 It is a diagram schematically illustrating a production method according to an embodiment of the present invention. Figure 2 (a) is a diagram illustrating a manufacturing method when a raw material input unit is provided as another structure, Figure 2 (b) is a diagram illustrating a production method in which a sulfide-based solid electrolyte discharge portion is provided as another structure.

[0038] Figure 3 This is a flowchart illustrating a production method according to an embodiment of the present invention.

[0039] Figure 4 It is a diagram schematically illustrating a production method according to an embodiment of the present invention.

[0040] Figure 5 This is a flowchart illustrating a production method according to an embodiment of the present invention. Figure 5 (a) is a flow chart illustrating the process of introducing a gas containing sulfur element into the first space. Figure 5 (b) is a flow chart illustrating the case where a solid containing sulfur element is introduced into the first space. DETAILED DESCRIPTION

[0041] The present invention is described in detail below, but the present invention is not limited to the following embodiments and can be implemented in any manner without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used to include the numerical values ​​recorded before and after it as the lower limit and upper limit. In addition, in the following drawings, parts and locations that play the same role are sometimes marked with the same symbols and described, and repeated descriptions are sometimes omitted or simplified. In addition, the embodiments described in the drawings are modeled for the purpose of clearly describing the present invention, and do not necessarily accurately represent the dimensions and scales of actual devices, etc.

[0042] <Method for producing sulfide-based solid electrolyte>

[0043] The method for producing a sulfide-based solid electrolyte according to the present embodiment (hereinafter, also referred to as the present production method) is a method for producing a sulfide-based solid electrolyte in which a raw material is heated and melted in a heating furnace. In the present production method, the heating furnace comprises: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside. In the present production method, a melt is formed by heating and melting the raw material, and the melt and the gap between the heating furnace are separated into a first space where the sulfur supply unit is located and a second space where the other structures are located by the partition, and a sulfur-excess atmosphere is formed by introducing a component containing sulfur element from the sulfur supply unit into the first space.

[0044] (Sulfide-based solid electrolyte)

[0045] In the present manufacturing method, the type and composition of the manufactured sulfide-based solid electrolyte are not particularly limited and can be appropriately selected according to the application, desired physical properties, etc. As the sulfide-based solid electrolyte, for example, a sulfide-based solid electrolyte containing Li, P and S, a sulfide-based solid electrolyte containing Li, P, S and Ha, etc. can be cited. Here, Ha represents at least one element selected from the halogen elements. Specifically, Ha is, for example, at least one element selected from F, Cl, Br and I. In order to obtain a argyrodite-type crystal structure, as Ha, it is more preferred to contain at least one of Cl and Br, and it is further preferred to contain Cl, and it is further preferred to contain Cl alone or a mixture of Cl and Br.

[0046] The sulfide-based solid electrolyte may be an amorphous sulfide-based solid electrolyte, a sulfide-based solid electrolyte having a specific crystal structure, or a sulfide-based solid electrolyte including a crystalline phase and an amorphous phase, depending on its purpose.

[0047] From the viewpoint of improving lithium ion conductivity, the sulfide-based solid electrolyte preferably contains a crystal structure. In the case where the sulfide-based solid electrolyte contains a crystal structure, the crystal contained in the sulfide-based solid electrolyte is preferably an ion-conducting crystal. Specifically, the ion-conducting crystal refers to a crystal having a lithium ion conductivity preferably greater than 10 －4 S / cm, more preferably greater than 10 －3 S / cm crystals.

[0048] More specifically, the sulfide-based solid electrolyte includes Li 10 G 2 S 12 Sulfide-based solid electrolytes containing LGPS-type crystals, Li 6 PS 5 Cl 1Sulfide solid electrolytes of argyrodite-type crystals, Li-P-S-Ha glass-ceramics, and Li 7 P 3 S 11 The sulfide-based solid electrolyte may be a sulfide-based solid electrolyte obtained by combining the above, or a sulfide-based solid electrolyte containing a plurality of crystals having different compositions and crystal structures. From the perspective of excellent lithium ion conductivity, a sulfide-based solid electrolyte containing argyrodite-type crystals is preferred as the sulfide-based solid electrolyte.

[0049] When the sulfide-based solid electrolyte contains crystals, the crystal structure preferably includes argyrodite from the viewpoint of the symmetry of the crystal structure. Crystals with high symmetry are preferred when forming powders because the paths for lithium ion conduction are easily extended three-dimensionally.

[0050] In order to obtain an argyrodite type crystal structure, the crystal phase contains Ha in addition to Li, P and S. Ha more preferably contains at least one of Cl and Br, further preferably contains Cl, and further preferably is a single substance of Cl or a mixture of Cl and Br.

[0051] Argentite-type crystals can be defined as crystals containing Li, P, S and Ha and having peaks at 2θ=15.7±0.5° and 30.2±0.5° in an X-ray powder diffraction (XRD) pattern. In addition to the above, the XRD pattern preferably has a peak at 2θ=18.0±0.5°, and more preferably has a peak at 2θ=25.7±0.5°.

[0052] The composition of the sulfide-based solid electrolyte can be determined by composition analysis using, for example, ICP emission spectroscopy, atomic absorption spectrometry, ion chromatography, etc. In addition, the type of crystals contained in the sulfide-based solid electrolyte can be analyzed from an X-ray powder diffraction (XRD) pattern.

[0053] (raw material)

[0054] The raw materials used in the present production method can use the raw materials known as the raw materials of the various sulfide-based solid electrolytes mentioned above. For example, in the case where the sulfide-based solid electrolyte contains Li, P and S, the raw materials contain lithium element (Li), sulfur element (S) and phosphorus element (P). As such raw materials, substances (components) containing Li such as Li simple substance and compounds containing Li, substances (components) containing S such as S simple substance and compounds containing S, substances (components) containing P such as P simple substance and compounds containing P, etc. can be used in appropriate combinations. The compounds containing Li, the compounds containing S and the compounds containing P may also be compounds containing two or more selected from Li, S and P at the same time. For example, as a compound serving as both a compound containing S and a compound containing P, phosphorus pentasulfide (P) can be cited. 2 S 5 )wait.

[0055] As a substance containing Li, for example, lithium sulfide (Li 2 S), lithium carbonate (Li 2 CO 3 ), lithium sulfate (Li 2 SO 4 ), lithium oxide (Li 2 O) and lithium compounds such as lithium hydroxide (LiOH), metallic lithium, etc. From the viewpoint of easy handling, lithium sulfide is preferably used.

[0056] On the other hand, since lithium sulfide is expensive, it is preferred to use lithium compounds other than lithium sulfide, metallic lithium, etc. from the viewpoint of suppressing the manufacturing cost of sulfide-based solid electrolytes. Specifically, in this case, the raw material preferably contains a lithium compound selected from metallic lithium, lithium carbonate (Li 2 CO 3 ), lithium sulfate (Li 2 SO 4 ), lithium oxide (Li 2 As the substance containing Li, one or more of lithium ion (LiO) and lithium hydroxide (LiOH) may be used. These substances may be used alone or in combination of two or more.

[0057] Examples of the substance containing 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 , iron sulfide (FeS, Fe 2 S 3 , FeS 2 , Fe1－x S, etc.), bismuth sulfide (Bi 2 S 3 ), copper sulfide (CuS, Cu 2 S, Cu 1－x From the viewpoint of suppressing the inclusion of elements other than the elements constituting the target sulfide-based solid electrolyte, the substance containing S is preferably phosphorus sulfide, and more preferably 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 that serves as both a substance containing S and a substance containing P.

[0058] Examples of substances containing 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 and elemental phosphorus, etc. From the viewpoint of suppressing the inclusion of elements other than the elements constituting the target sulfide-based solid electrolyte, the substance containing P is preferably phosphorus sulfide, and more preferably phosphorus pentasulfide (P 2 S 5 ). These substances may be used alone or in combination of two or more.

[0059] In the present production method, the raw material is obtained in the form of a mixed raw material, for example, by 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, the molar ratio of Li to P in the raw material, Li / P, is preferably 65 / 35 or more, more preferably 70 / 30 or more.

[0060] An example of a preferred combination of the above compounds is Li 2 S and P 2 S 5 Combination of. 2 S and P 2 S 5 In the case of Li / P, the molar ratio of Li to P is preferably 65 / 35 to 88 / 12, more preferably 70 / 30 to 88 / 12. 2 S 5 Relative to Li 2 S becomes less, thus easily suppressing the 2 S 5 The boiling point is lower than Li 2 The melting point of S causes the release of sulfur and phosphorus during heat treatment.

[0061] The raw material of the present production method may further contain other substances (compounds, etc.) in addition to the above substances, depending on the composition of the target sulfide-based solid electrolyte or as an additive, etc.

[0062] For example, in the case of manufacturing a sulfide-based solid electrolyte containing a halogen element such as F, Cl, Br or I, the raw material preferably contains a halogen element (Ha). In this case, the raw material preferably comprises a compound containing a halogen element. As a compound containing a halogen element, lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI) and other lithium halides, phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, boron halides, etc. can be cited. As a compound containing a halogen element, from the viewpoint of suppressing the presence of elements other than the elements constituting the target sulfide-based solid electrolyte, lithium halides are preferred, and LiCl, LiBr, and LiI are more preferred. These compounds can be used alone or in combination with two or more.

[0063] In addition, lithium halide is also a compound containing Li. When the raw material contains lithium halide, a part or all of Li in the raw material may be derived from lithium halide.

[0064] When the raw material contains a halogen element, from the viewpoint of lowering the melting point when the raw material is heated and melted, the molar equivalent of Ha relative to P in the raw material is preferably 0.2 molar equivalent or more, more preferably 0.5 molar equivalent or more. In addition, from the viewpoint of improving the stability of the obtained sulfide-based solid electrolyte, the molar equivalent of Ha is preferably 4 molar equivalents or less, more preferably 3 molar equivalents or less.

[0065] From the viewpoint of improving the glass formation state of the obtained sulfide-based solid electrolyte, it is also preferred that the raw material contains SiS 2 , B 2 S 3 ,GeS 2 、Al 2 S 3 By making glass formation easier, glass can be obtained even if the cooling rate is reduced when glass is obtained by rapid cooling, which can reduce the load on equipment. In addition, from the perspective of imparting moisture resistance to the sulfide-based solid electrolyte, it is also possible to selectively contain SiO 2 , B 2 O 3 ,GeO 2 、Al 2 O 3 , P 2 O 5 These compounds may be used alone or in combination of two or more.

[0066] The amount of these compounds added is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, relative to the total amount of the raw materials, and preferably 50% by weight or less, more preferably 40% by weight or less.

[0067] As raw materials, the above-mentioned various substances can be used in combination. When a plurality of substances are combined as raw materials, for example, the raw materials can be mixed using a known mixer or the like. As the mixer, for example, a V-type mixer, a W-type mixer, a ribbon mixer or the like can be used.

[0068] In the present manufacturing method, a sulfide-based solid electrolyte is obtained by heating and melting the raw materials, and the raw materials may be heat-treated in advance before heating and melting. By heat-treating, the raw materials can be heated and melted from a state where the composition is closer to the target composition, so it is easy to control the composition. It should be noted that part of the raw materials may also be heat-treated and then mixed with the remaining raw materials. The heat-treated raw materials may include, for example, Li 4 P 2 S 6 , Li 3 PS 4 and the like, a compound containing Li, P and S. The conditions for the heat treatment are not particularly limited, but for example, it is preferably maintained at a temperature of 100 to 500° C. for 0.1 to 5 hours.

[0069] (Method for producing sulfide-based solid electrolyte)

[0070] Figure 1 : is a flowchart showing an example of the present manufacturing method. For example, the present manufacturing method includes: step S11, forming a molten metal by heating and melting a raw material; step S12, separating the molten metal and the gap of the heating furnace into a first space where a sulfur supplying part is located and a second space where other structures are located by a partition; and step S13, forming a sulfur-excess atmosphere part by introducing a component containing sulfur element from the sulfur supplying part into the first space. It should be noted that steps S11 to S13 do not need to be performed in this order, and may be performed in parallel, for example.

[0071] Figure 2 It is a figure which schematically illustrates this manufacturing method. Figure 2 (a) is a diagram illustrating the present manufacturing method when a raw material input section is provided as another structure, Figure 2 (b) is a diagram illustrating the present production method when a sulfide-based solid electrolyte discharge portion is provided as another structure.

[0072] exist Figure 2 In the present invention, the manufacturing device 100 includes at least a heating furnace 10. The heating furnace 10 includes a sulfur supply unit 13, a partition 19 provided inside the heating furnace 10, and other structures that can connect the inside and outside of the heating furnace 10. Figure 2 In (a), the heating furnace 10 includes a raw material input unit 11 as another structure. Figure 2 In (b), the heating furnace 10 includes a sulfide-based solid electrolyte discharge portion 15 as another structure.

[0073] The present production method includes heating and melting the raw material in a heating furnace (heating and melting step). Specifically, in the heating and melting step, the raw material is heated and melted in a heating furnace to form a melt (step S11).

[0074] exist Figure 2 In the heating furnace 10, the melt 5 obtained by heating and melting the raw material is provided therein. Then, the gap between the melt 5 and the heating furnace 10 is separated into a first space where the sulfur supply unit 13 is located and a second space where other structures are located by the partition 19 (step S12). In addition, the sulfur-excess atmosphere section 23 is formed by introducing a component containing sulfur element from the sulfur supply unit 13 into the first space (step S13).

[0075] For example, in Figure 2 In (a), the raw material is heated and melted to form a melt 5, and the gap between the melt 5 and the heating furnace 10 is separated into a first space where the sulfur supply part 13 is located and a second space where the raw material input part 11 is located by the partition 19. Then, a component containing sulfur element is introduced into the first space to form a sulfur-excess atmosphere part 23.

[0076] For example, in Figure 2 In (b), the raw material is heated and melted to form a melt 5, and the melt 5 and the gap between the heating furnace 10 are separated into a first space where the sulfur supply part 13 is located and a second space where the sulfide-based solid electrolyte discharge part 15 is located by the partition 19. In addition, a sulfur-excess atmosphere part 23 is formed by introducing a component containing sulfur element into the first space.

[0077] It should be noted that, here, the second space where other structures are located is as follows Figure 2 In the case where other structures are in contact with the gas atmosphere in the heating furnace, as in (a), it refers to the other structures and the gas atmosphere that the other structures are in contact with. Figure 2 In (a), the second space where the raw material input part 11 is located includes the raw material input part 11 and the gas atmosphere part 21 in contact with the raw material input part 11 .

[0078] On the other hand, Figure 2 As in (b), when the other structure is in contact with the melt in the heating furnace, the other structure and the gas atmosphere portion where the other structure is first released when the amount of the melt in the heating furnace is reduced are the second space where the other structure is located. Figure 2In (b), the second space where the sulfide-based solid electrolyte discharge portion 15 is located is the gas atmosphere portion 21 with which the sulfide-based solid electrolyte discharge portion 15 first contacts when the amount of the melt 5 is reduced.

[0079] In this specification, the gas atmosphere portion refers to a gas atmosphere region divided by the melt or a partition or the like in the heating furnace.

[0080] Generally, in a heating furnace, the temperature is likely to drop near other structures such as a raw material input part and a sulfide-based solid electrolyte discharge part that allow the inside and outside of the heating furnace to communicate. More specifically, in the case of the raw material input part, the P contained in the raw material may be 2 S 5 The melting point is relatively low, at 288°C, so if the outlet temperature is not lowered to some extent, it is possible that P 2 S 5 liquefaction and blockage. In addition, when the melt is discharged from the sulfide-based solid electrolyte discharge part, the discharged melt can be cooled, so there is a tendency for the temperature to be lower than that of the furnace body. In addition, even if these other structures can be switched and the component is in a closed state, there is a situation where the temperature of the other structure is easy to drop depending on the mechanism and position of the switch control. For example, in the structure of a switch control mechanism such as a valve arranged in the middle of the path connecting the inside and the outside of the heating furnace, it is believed that the temperature is easy to drop near other structures.

[0081] Moreover, the above-mentioned sulfur-excess atmosphere section is composed of a gas containing sulfur. If the gas containing sulfur comes into contact with a portion with a lower temperature in the heating furnace, sulfur is likely to liquefy or solidify in that portion. That is, sulfur may adhere to the vicinity of other structures. In particular, if adhesion occurs when the inside and outside of the heating furnace are connected by other structures, blockage may sometimes occur near other structures. In addition, when the internal pressure of the furnace rises due to blockage and sulfur vapor leaks to the outside, sulfur also adheres to external piping and components, increasing the risk of difficulty in continuing production. In addition, when the input of materials into the heating furnace and the discharge of materials from the heating furnace are hindered due to blockage, the risk of difficulty in continuing production also increases.

[0082] In general, the higher the temperature, the higher the saturated vapor pressure of sulfur, and sulfur gas tends to exist at a high concentration. Therefore, in the present production method, which heats and melts at a higher temperature than solid phase reaction, for example, sulfur deposition in the sulfur-excess atmosphere is likely to occur.

[0083] In contrast, in the present manufacturing method, the gap between the melt and the heating furnace is separated into a first space where the sulfur supplying section is located and a second space where other structures are located by the partitioning section, and a sulfur-excessive atmosphere section is formed in the first space. Thus, the sulfur-excessive atmosphere section is separated independently from other structures, so that the adhesion of sulfur and the clogging of the inside of the device caused by the adhesion can be suppressed, and the production can be continued stably easily, thereby improving the productivity.

[0084] As long as other structures are components that can connect the inside and outside of the heating furnace, there is no special limitation. For example, components for transferring substances to the inside of the heating furnace, components for discharging substances from the inside of the heating furnace, etc. can be cited. The above-mentioned other structures are more specifically preferably at least one of the above-mentioned raw material input part and the sulfide-based solid electrolyte discharge part. Other structures can be openings that always connect the inside and outside of the heating furnace, or switchable components that connect the inside and outside of the heating furnace when controlled to an open state. In other structures, the opening method, the switch mechanism, etc. are not particularly limited and can be well-known. For example, as examples of the form of other structures, a form with an opening (connecting part) on the wall of the heating furnace, a form in which a pipe (nozzle) that can communicate with the outside of the heating furnace is arranged in the heating furnace, etc.

[0085] In addition, the communication between the inside and outside of the heating furnace using components may not be intentionally controlled. There are also cases where components such as stirring blades, thermocouples, and pressure gauges are installed in the heating furnace, so that the gas in the heating furnace has to leak from the connection between the component and the heating furnace. The connection may have other structures. The temperature near such a connection is likely to drop. In addition, if sulfur is attached, the operation of the component may be affected, thereby reducing productivity. By suppressing the attachment of sulfur near the connection, it can help improve productivity.

[0086] From the viewpoint of appropriately obtaining the effect of suppressing the liquefaction or solidification of sulfur, the lowest temperature of the second space where the other structures are located is preferably 450° C. or lower, more preferably 400° C. or lower, and further preferably 350° C. or lower. This means that the lowest temperature of the second space is equal to or lower than the boiling point of sulfur, 444° C. That is, in this case, it becomes a condition that the liquefaction and solidification of sulfur are relatively easy to occur, so the effect of the present invention can be more appropriately obtained.

[0087] Here, the lowest temperature of the second space refers to the lowest temperature of the region into which sulfur vapor can penetrate when there is no partition in the heating furnace. In most cases, it is the temperature of the portion farthest from the furnace body that allows the outside and the inside to communicate. The lower limit of the lowest temperature is not particularly limited, and is, for example, about 100°C in practice.

[0088] As described above, the other structure is a component that allows the inside and outside of the heating furnace to communicate, but when the inside and outside of the heating furnace are communicated by the other structure, that is, when the other structure is in an open state, the risk of blockage due to temperature drop and sulfur adhesion is more likely to increase. Therefore, when the manufacturing method further includes a step of communicating the inside and outside of the heating furnace by using at least one of the other structures in a state where the heating furnace has an excess sulfur atmosphere, it is preferred that the second space includes the other structure that communicates the inside and outside of the heating furnace.

[0089] Figure 3 This is a flowchart illustrating the present manufacturing method when the method further includes a step of communicating the inside and the outside of the heating furnace using at least one of other structures. Figure 3 The manufacturing method illustrated includes steps S21 to S23 corresponding to the above-mentioned steps S11 to S13 and step S24 of connecting the inside and the outside of the heating furnace by at least one other structure in a state where the sulfur-excess atmosphere portion is provided in the heating furnace.

[0090] It should be noted that, as exemplified below, the order of steps S21 to S24 is not particularly limited. For example, at least one of steps S21 to S23 and step S24 may be performed in parallel, or step S24 may be performed multiple times in the middle of at least one of steps S21 to S23, or step S24 may be performed after steps S21 to S23.

[0091] For example, in Figure 2 In (a), when the raw materials and the like are continuously introduced into the heating furnace from the raw material input part in parallel with the heating and melting step, the raw material input part 11 is opened in a state where the sulfur-excess atmosphere part 23 is provided in the heating furnace 10, so that the inside and outside of the heating furnace can be communicated. In this case, the step of communicating the inside and outside of the heating furnace by using the raw material input part is equivalent to Figure 3 Step S24 in the above. Figure 2 In the configuration (a), the gap between the melt 5 and the heating furnace 10 is separated into a first space where the sulfur supply unit 13 is located and a second space where the raw material input unit 11, which is another structure that allows the inside and outside of the heating furnace to communicate, is located by the partition 19. That is, the second space includes another structure that allows the inside and outside of the heating furnace to communicate.

[0092] In addition, Figure 2 In (b), for example, when the melt 5 is discharged from the heating furnace after the heating and melting step, the sulfide-based solid electrolyte discharge portion 15 is opened in a state where the sulfur-excess atmosphere portion 23 and the melt 5 are provided in the heating furnace 10, so that the inside and outside of the heating furnace can be connected. In this case, the inside and outside of the heating furnace can be connected by the sulfide-based solid electrolyte discharge portion. Figure 3 At this time, the gap between the melt 5 and the heating furnace 10 is separated into a first space where the sulfur supply unit 13 is located and a second space where the sulfide-based solid electrolyte discharge unit 15, which is another structure that allows the inside and outside of the heating furnace to communicate, is located by the partition 19. That is, the second space includes another structure that allows the inside and outside of the heating furnace to communicate.

[0093] It should be noted that Figure 2 In the example, the heating furnace is provided with at least one other structure, but the heating furnace may also be provided with two or more other structures. In addition, in this case, there may be multiple second spaces where the other structures are located. When the heating furnace has multiple other structures, the first space only needs to be separated from the second space where at least one of the other structures is located, and may also be separated from all the second spaces where the other structures are located.

[0094] For example, Figure 4 This is a diagram schematically illustrating the present manufacturing method when the heating furnace includes a raw material input portion and a sulfide-based solid electrolyte discharge portion as other structures, and the first space is separated from the two areas respectively including these. Figure 4 In the present invention, the manufacturing device 100 includes at least a heating furnace 10. The heating furnace 10 includes a sulfur supply unit 13, partitions 19a and 19b provided inside the heating furnace, and other structures that can connect the inside and outside of the heating furnace. Figure 4 In the embodiment, the heating furnace 10 includes a raw material input portion 11 and a sulfide-based solid electrolyte discharge portion 15 as other structures.

[0095] exist Figure 4 In the embodiment, the gap between the melt and the heating furnace is separated into a first space where the sulfur supply unit 13 is located and a second space where the raw material input unit 11 as another structure is located by the partition 19a. Furthermore, the gap between the melt and the heating furnace is separated into a first space where the sulfur supply unit 13 is located and a second space where the sulfide-based solid electrolyte discharge unit 15 as another structure is located by the partition 19b.

[0096] Here, in Figure 4 In the above, the second space where the raw material input part 11 is located refers to the raw material input part 11 and the gas atmosphere part 21a, and the second space where the sulfide-based solid electrolyte discharge part 15 is located refers to the sulfide-based solid electrolyte discharge part 15 and the gas atmosphere part 21b. Moreover, the sulfur-excess atmosphere part 23 is formed in the above-mentioned first space. Figure 4 In the embodiment, the sulfur-excess atmosphere section 23 is separated from both the second space where the raw material input section 11 is located and the second space where the sulfide-based solid electrolyte discharge section 15 is located.

[0097] For example, Figure 4In the manufacturing method illustrated, the heating and melting step can be continuously performed by feeding the raw material from the raw material feeding part 11 and discharging the melt from the sulfide-based solid electrolyte discharging part 15 in parallel with the heating and melting step. At this time, the raw material feeding part 11 and the sulfide-based solid electrolyte discharging part 15 are both components that connect the inside and outside of the heating furnace in a state where the above-mentioned sulfur-excess atmosphere part is provided in the heating furnace. Therefore, by separating the sulfur-excess atmosphere part from the second space where they are respectively located, it is possible to effectively suppress the adhesion of sulfur in the case of continuously performing the heating and melting step as described above.

[0098] Hereinafter, the present production method will be described in more detail.

[0099] (Heating furnace)

[0100] In the present production method, the heating furnace includes a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside and the outside of the heating furnace.

[0101] The sulfur supply unit is not particularly limited as long as it can introduce a component containing sulfur element into the heating furnace, and may be a known configuration corresponding to a method of introducing a component containing sulfur element.

[0102] The partition is provided inside the heating furnace. Its specific shape, material, etc. are not particularly limited within the scope of achieving the effect of the present invention. Figure 2 and Figure 4 The partition 19 in the figure is a plate-shaped member provided to separate the melt from the space of the heating furnace and to partition at least the gas atmosphere portion in the heating furnace. Figure 2 and Figure 4 The partition 19 in FIG. 1 is arranged parallel to the cross section of the heating furnace 10 along the vertical direction when the up-down direction of the paper is defined as the vertical direction.

[0103] When the partition is provided with molten metal in the heating furnace, it is preferred that the gas atmosphere portion is divided by the partition and the molten metal, and the molten metal is not completely divided but is arranged in a manner that the surface and the back surface of the partition are connected. Such a connecting portion for connecting the molten metal is preferably provided on the bottom side of the heating furnace. Thus, even when the amount of the molten metal is small, it is easy to maintain the state in which the molten metal and the gap of the heating furnace are separated by the partition. One or more partitions may be provided in the heating furnace.

[0104] The other structures are components that can make the inside and outside of the heating furnace communicate with each other as described above. Specific components and the like cited as other structures are as exemplified above.

[0105] The position of the opening of the other structure in the heating furnace is preferably located above the lower end of the partition that contacts the second space where the other structure is located. The up-down direction here refers to the up-down direction of the heating furnace when it is set up for use. Figure 4 In the embodiment, the opening of the raw material input part 11 in the heating furnace is located above the lower end of the partition 19a that is disconnected from the second space where the raw material input part 11 is located. In addition, the opening of the sulfide-based solid electrolyte discharge part 15 in the heating furnace is located above the lower end of the partition 19b that is disconnected from the second space where the sulfide-based solid electrolyte discharge part 15 is located. Thus, even when the amount of the molten liquid in the heating furnace is reduced due to the discharge of the molten liquid, etc., it is easy to maintain the state in which the first space and the second space are separated by the partition. In addition, when the present manufacturing method includes the step of discharging the molten liquid from the sulfide-based solid electrolyte discharge part in a state in which the sulfur-excess atmosphere part is provided in the heating furnace, it is easy to stop the discharge of the molten liquid while maintaining the first space (sulfur-excess atmosphere part) in a separated state, and the adhesion of sulfur in the sulfide-based solid electrolyte discharge part can be more appropriately suppressed.

[0106] It should be noted that the openings in the heating furnace of other structures refer to the openings on the inner side of the heating furnace when the inside and outside of the heating furnace are connected by other structures. Figure 2 and Figure 4 When the wall of the heating furnace has an opening (connecting portion) such as the sulfide-based solid electrolyte discharge portion 15 in the figure, this is the opening; when a pipe (nozzle) that can communicate with the outside of the heating furnace is arranged in the heating furnace, this is the opening of the pipe on the inner side of the heating furnace.

[0107] (Heating and melting process)

[0108] In the heating and melting step, the raw material is heated and melted in a heating furnace. More specifically, in the heating and melting step, the raw material is heated and melted in a heating furnace to form a melt. In addition, by heating and melting the raw material in the heating furnace, a sulfur-excess atmosphere portion is formed in the first space, so that the raw material (melt) contacts the sulfur-excess atmosphere portion and is heated and melted.

[0109] The method of feeding the raw materials into the heating furnace is not particularly limited, and can be appropriately selected from known methods according to the desired manufacturing method, etc. As a method of feeding the raw materials into the heating furnace, for example, a method of feeding the raw materials into the heating furnace from the above-mentioned raw material feeding part can be cited. The raw materials can be fed continuously in a fixed amount, or a specified amount can be fed intermittently. In addition, in order to suppress the outflow of gas in the heating furnace from the raw material feeding part, an inert gas or the like can be introduced from the raw material feeding part. As the inert gas, for example, nitrogen, argon, etc. can be cited.

[0110] The heating temperature in the heating and melting process is preferably 600°C to 900°C. The heating temperature is preferably 600°C or more, more preferably 650°C or more, and further preferably 700°C or more. The heating temperature is preferably 900°C or less, more preferably 850°C or less, and further preferably 800°C or less. The heating temperature is preferably 900°C or less, more preferably 850°C or less, and further preferably 800°C or less. The heating temperature is preferably 900°C or less, more preferably 850°C or less, and further preferably 800°C or less. The heating temperature is preferably 900°C or less, more preferably 850°C or less, and the amount of components separated from the raw material during heating and melting is not easy to be excessive.

[0111] The method for heating the heating furnace is not particularly limited, and for example, a known heating method such as using an external heating device may be used.

[0112] From the perspective of improving the homogeneity of the melt and the obtained sulfide-based solid electrolyte, the heating and melting time is preferably 0.1 hours or more, more preferably 0.5 hours or more, more preferably 0.7 hours or more, and more preferably 1 hour or more. In addition, as long as the degradation and decomposition of the components in the melt caused by heating are within an allowable range, the upper limit of the heating and melting time is not particularly limited and can be longer. As a realistic range, it is preferably less than 100 hours, more preferably less than 50 hours, and more preferably less than 24 hours. As described above, heating and melting can be carried out continuously or batchwise.

[0113] The pressure during heating and melting is not particularly limited, but is preferably normal pressure or slightly increased pressure, and more preferably normal pressure.

[0114] (Sulfur Excessive Atmosphere)

[0115] The sulfur-excess atmosphere portion is formed by introducing a component containing sulfur from the sulfur supply portion into the first space. The sulfur-excess atmosphere portion is a gas atmosphere portion composed of a gas atmosphere containing sulfur. The raw material (melt) is heated and melted by contact with the sulfur-excess atmosphere portion, and volatilization of the sulfur component into the sulfur-containing gas atmosphere with a large sulfur partial pressure can be suppressed. As a result, the composition of the obtained sulfide-based solid electrolyte can be easily controlled.

[0116] As a method for forming the sulfur-excess atmosphere portion, as described above, there is a method of introducing a component containing sulfur element from the sulfur supply portion into the heating furnace in the first space. More specifically, there is a method of introducing at least one of a gas containing sulfur element and a solid containing sulfur element into the first space. As for the timing of introducing the component containing sulfur element into the heating furnace, it may be after the raw material is previously placed in the heating furnace and heated to obtain a melt, or it may be performed in parallel with placing the raw material in the heating furnace as long as the effect of the present invention is not impaired. From the viewpoint of suppressing the adhesion of sulfur to the raw material input portion, it is more preferable to introduce the component containing sulfur element after heating to obtain a melt.

[0117] As a method of introducing the sulfur-containing gas, for example, there can be mentioned a method of introducing the sulfur-containing gas prepared in advance outside the heating furnace into the first space. The method of preparing the sulfur-containing gas outside the heating furnace is not particularly limited, and for example, it is preferable to heat a sulfur source outside the heating furnace to obtain the sulfur-containing gas.

[0118] Figure 5 (a) is a flow chart illustrating the method. Figure 5 The manufacturing method illustrated in (a) includes: step S311 of heating a sulfur source at 200°C to 450°C outside a heating furnace to obtain a gas containing sulfur element, and steps S312 to S314 corresponding to the above-mentioned steps S11 to S13. The order of steps S311 to S314 is not particularly limited, for example, step S311 may be performed before steps S312 to S314, or may be performed in parallel with steps S312 to S314.

[0119] The sulfur source is not particularly limited as long as it is a single sulfur or sulfur compound that can produce a gas containing sulfur by heating. Examples thereof include single 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.

[0120] For example, these sulfur sources are heated by a separately provided sulfur source heating unit to generate a gas containing sulfur element, and N 2 An inert gas such as argon gas or helium gas is supplied to the heating portion as a carrier gas, thereby forming a sulfur-excess atmosphere portion.

[0121] The temperature for heating the sulfur source can be appropriately selected according to the type of the sulfur source used. For example, the temperature for heating the sulfur source is preferably 200°C to 450°C, and more preferably 300°C to 400°C.

[0122] Alternatively, the sulfur-excess atmosphere portion may be formed by introducing a solid containing sulfur into the first space. In this case, the sulfur-excess atmosphere portion may be formed by heating the solid containing sulfur in the heating furnace to obtain a sulfur-containing gas. Figure 5 (b) is a flow chart illustrating the method. Figure 5The manufacturing method exemplified in (b) includes steps S321 and S322 corresponding to the above-mentioned steps S11 and S12, and step S323 of introducing a solid containing elemental sulfur as a component containing elemental sulfur from a sulfur supply unit into the first space to form a sulfur-excess atmosphere unit.

[0123] Examples of the solid containing sulfur include elemental sulfur, H 2 S.Bi 2 S 3 , iron sulfide, copper sulfide, CS 2 For example, the solid sulfur source can be introduced into the heating furnace by transporting the solid sulfur source in a fine state such as powder to the heating part by a carrier gas. It should be noted that the method of introducing the component containing sulfur into the heating furnace can be to introduce the solid sulfur source into the heating furnace. Figure 5 A method that combines (a) and (b) of Figure 5 Step S314 in (a) is changed to Figure 5 Step S323 in (b).

[0124] In the sulfur excess atmosphere section, the sulfur partial pressure is preferably set to 10 －3 ~10 0 By setting the sulfur partial pressure to the above, sulfur can be introduced efficiently at low cost without complicating the apparatus.

[0125] (Gas atmosphere section)

[0126] In the heating furnace, the water dew point of the gas atmosphere separated from the first space is preferably lower than -30°C, more preferably lower than -40°C, and further preferably lower than -50°C. This can prevent the water present in the gas atmosphere from reacting with the raw material or the melt and affecting the composition of the obtained sulfide-based solid electrolyte. The lower limit of the water dew point of the gas atmosphere is not particularly limited, and is, for example, about -80°C.

[0127] In addition, in the heating furnace, the oxygen concentration of the gas atmosphere separated from the first space is preferably less than 100 ppm, more preferably less than 50 ppm, and further preferably less than 10 ppm. This can prevent the oxygen present in the gas atmosphere from reacting with the raw material or the melt and affecting the composition of the obtained sulfide-based solid electrolyte. The lower limit of the oxygen concentration in the gas atmosphere is not particularly limited, and is, for example, about 0.01 ppm.

[0128] (Cooling process)

[0129] The present manufacturing method preferably further comprises a step of cooling the melt obtained by heating and melting to obtain a solid. The cooling can be performed by a known method, and the method is not particularly limited. After the heating and melting step, the melt can be continued to be cooled in the heating furnace, or the melt can be taken out of the heating furnace for cooling. When the melt is taken out of the heating furnace for cooling, the melt is discharged from the above-mentioned sulfide-based solid electrolyte discharge portion, for example.

[0130] As a more specific method of cooling, for example, a method of cooling the molten metal by flowing out onto a plate-like body such as carbon, a method of thinly molding by flowing into a narrow gap, etc. can be cited. When the molten metal flows out onto a plate-like body for cooling, from the viewpoint of improving the cooling efficiency, the thickness of the molten metal after flowing out and the obtained solid is preferably thinner. Specifically, the thickness is preferably less than 10 mm, more preferably less than 5 mm. The lower limit of the thickness is not particularly limited, and may be more than 0.01 mm, or more than 0.02 mm. When flowing into a narrow gap and thinly molding, the cooling efficiency is excellent, and a flaky molded body, a fibrous molded body, a powdery molded body, etc. can be obtained. The obtained solid is crushed into a size that is easy to handle and obtained in any shape. Among them, it is easy to recycle when obtained as a block solid, so it is preferred. The block also includes the case of being plate-like, flaky or fibrous.

[0131] From the viewpoint of maintaining the composition obtained by the heating and melting process, the cooling rate is preferably 0.01°C / sec or more, more preferably 0.05°C / sec or more, and further preferably 0.1°C / sec or more. In addition, the upper limit of the cooling rate is not particularly limited, but it is generally believed that the cooling rate of the twin rolls with the fastest rapid cooling rate is 1,000,000°C / sec or less.

[0132] Here, when the solid desired to be obtained is an amorphous sulfide-based solid electrolyte, it is preferred to obtain the solid by quenching the melt obtained by heating and melting. 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 rolls with the fastest quenching rate is 1,000,000°C / sec or less.

[0133] On the other hand, slow cooling can also be performed during the cooling process to crystallize at least a portion of the solid, thereby obtaining 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 / sec or more, more preferably 0.05°C / sec or more. In addition, the cooling rate is preferably 500°C / sec or less, more preferably 450°C / sec or less. The cooling rate may be less than 10°C / sec, or may be 5°C / sec or less. It should be noted that the cooling rate may be appropriately adjusted according to the conditions of crystallization.

[0134] Here, the crystal contained in the sulfide-based solid electrolyte is preferably an ion-conducting crystal. Specifically, the ion-conducting crystal refers to a crystal having a lithium ion conductivity greater than 10 －4 S / cm, more preferably greater than 10 －3 S / cm crystals.

[0135] When it is desired that the solid obtained after cooling is a sulfide-based solid electrolyte containing a crystalline phase, it is preferred that the melt obtained in the heating and melting step contains a compound that serves as a crystal nucleus. As a result, crystals are easily precipitated in the cooling step. The method of making the melt contain a compound that serves as a crystal nucleus is not particularly limited, and examples thereof include adding a compound that serves as a crystal nucleus to a raw material or a raw material heating material, and adding a compound that serves as a crystal nucleus to a melt during heating and melting.

[0136] Examples of the compound that serves as a crystal nucleus include oxides, nitrogen oxides, nitrides, carbides, chalcogenides, halides, etc. The compound that serves as a crystal nucleus is preferably a compound that has a certain degree of compatibility with the melt. It should be noted that a compound that is completely incompatible with the melt cannot serve as a crystal nucleus.

[0137] When it is desired that the solid obtained after cooling is a sulfide-based solid electrolyte containing a crystalline phase, the content of the compound that becomes the 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 the crystal nucleus in the melt is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0138] When it is desired that the solid obtained after cooling is an amorphous sulfide-based solid electrolyte, it is preferred that the melt does not contain a compound that serves as a crystal nucleus, or that the content of the compound is less than a predetermined amount. Specifically, the content of the compound that serves as a crystal nucleus in the melt is preferably less than 1% by mass, more preferably less than 0.1% by mass. The content of the compound that serves as a crystal nucleus in the melt may be less than 0.01% by mass.

[0139] The present production method may further include a step of performing a known post-treatment on the sulfide-based solid electrolyte obtained by cooling the melt. As the post-treatment step, for example, from the viewpoint of obtaining desired characteristics, a step of further heat-treating the sulfide-based solid electrolyte can be cited, and from the viewpoint of obtaining a desired shape, a step of pulverizing can be cited.

[0140] The present production method suppresses the adhesion of sulfur in the device, etc., and thus the productivity of the sulfide-based solid electrolyte is excellent. The sulfide-based solid electrolyte obtained by the present production method is suitable for use as a solid electrolyte material used in lithium-ion secondary batteries, etc.

[0141] <Sulfide-based solid electrolyte production device>

[0142] The manufacturing apparatus of the sulfide-based solid electrolyte according to the present embodiment (hereinafter, also referred to as the present manufacturing apparatus) is characterized in that it includes a heating furnace for heating and melting a raw material, the heating furnace includes: a sulfur supply part, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside, the partition part separates a melt formed by heating and melting the raw material in the heating furnace and a void of the heating furnace into a first space where the sulfur supply part is located and a second space where the other structures are located, and the sulfur supply part forms a sulfur-excess atmosphere part by introducing a component containing sulfur element into the first space.

[0143] The present production apparatus can be used to implement the present production method described above, and the contents described in the section "Production method of sulfide-based solid electrolyte" can be directly used.

[0144] Example

[0145] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. Examples 1 to 3 are Examples.

[0146] (Example 1)

[0147] use Figure 2A sulfide-based solid electrolyte is manufactured in a heating furnace having the structure illustrated in (a). First, a mixed raw material corresponding to the composition of the target sulfide-based solid electrolyte is prepared. Next, the mixed raw material is introduced from the raw material introduction section 11 of the heating furnace 10 to heat and melt to form a melt. The heating temperature is 700°C, and a heating source provided outside the heating furnace is used. Thus, the melt 5 and the gap between the heating furnace 10 are separated into a first space where the sulfur supply section 13 is located and a second space where the raw material introduction section 11 is located by the partition 19. In addition, solid sulfur is introduced into the first space from the sulfur supply section 13 of the heating furnace 10 to form a sulfur-excess atmosphere section 23. Heating is continued for 30 minutes in this state. Thus, the raw material (melt) is brought into contact with the sulfur-excess atmosphere section 23 and heated and melted. After heating, the melt 5 is continued to be cooled and solidified in the heating furnace 10 to obtain a sulfide-based solid electrolyte.

[0148] (Example 2)

[0149] use Figure 2 A sulfide-based solid electrolyte is manufactured in a heating furnace having the structure illustrated in (a). First, a mixed raw material corresponding to the composition of the target sulfide-based solid electrolyte is prepared. Next, the mixed raw material is introduced from the raw material input section 11 of the heating furnace 10 to heat and melt to form a melt. The heating temperature is 700°C, and a heating source provided outside the heating furnace is used. Thus, the melt 5 and the gap between the heating furnace 10 are separated into a first space where the sulfur supply section 13 is located and a second space where the raw material input section 11 is located by the partition 19. In addition, elemental sulfur as a sulfur source is heated at 350°C outside the heating furnace to obtain sulfur vapor. Then, a gas containing sulfur vapor is introduced from the sulfur supply section 13 of the heating furnace 10 into the first space to form a sulfur-excess atmosphere section 23. Heating is continued for 30 minutes in this state. Thus, the raw material (melt) is brought into contact with the sulfur-excess atmosphere section 23 and heated and melted. After heating, the melt is continued to be cooled and solidified in the heating furnace 10 to obtain a sulfide-based solid electrolyte.

[0150] (Example 3)

[0151] use Figure 2A sulfide-based solid electrolyte is manufactured in a heating furnace having the structure illustrated in (b). First, a mixed raw material corresponding to the composition of the target sulfide-based solid electrolyte is prepared. Next, the mixed raw material is introduced from the raw material introduction section (not shown) of the heating furnace 10 to heat and melt to form a melt. The heating temperature is 700°C, and a heating source provided outside the heating furnace is used. Thus, the melt 5 and the gap of the heating furnace 10 are separated into a first space where the sulfur supply section 13 is located and a second space where the sulfide-based solid electrolyte discharge section 15 is located by the partition 19. Next, solid sulfur is introduced from the sulfur supply section 13 of the heating furnace 10 into the first space to form a sulfur-excess atmosphere section 23. Heating is continued for 30 minutes in this state. Thus, the raw material (melt) is brought into contact with the sulfur-excess atmosphere section 23 and heated and melted. After heating, the melt 5 is discharged from the sulfide-based solid electrolyte discharge section 15, and is cooled and solidified by a double roller to obtain a sulfide-based solid electrolyte.

[0152] As described above, in all Examples 1 to 3, the gap between the melt and the heating furnace is separated into the first space where the sulfur supplying section is located and the second space where other structures are located by the partitioning section. Thus, the sulfur-excess atmosphere section is separated independently from other structures, and therefore, in all Examples 1 to 3, the adhesion of sulfur in the apparatus is suppressed, and productivity can be improved.

[0153] As described above, the following configurations are disclosed in this specification.

[0154] 1. A method for producing a sulfide-based solid electrolyte, comprising heating and melting a raw material in a heating furnace,

[0155] The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside.

[0156] The above raw materials are heated and melted to form a melt.

[0157] The partitioning portion separates the gap between the molten metal and the heating furnace into a first space where the sulfur supplying portion is located and a second space where the other structures are located.

[0158] A method for producing a sulfide-based solid electrolyte by introducing a component containing sulfur element from the sulfur supply part into the first space to form a sulfur-excess atmosphere part.

[0159] 2. The method for producing a sulfide-based solid electrolyte according to 1 above, wherein the other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

[0160] 3. The method for producing a sulfide-based solid electrolyte according to 1 or 2 above, wherein the lowest temperature of the second space is 450° C. or lower.

[0161] 4. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 3 above, further comprising the step of: in a state where the sulfur-excess atmosphere section is provided in the heating furnace, communicating the interior of the heating furnace with the exterior by using at least one of the other structures;

[0162] The second space includes another structure that allows the inside and outside of the heating furnace to communicate with each other.

[0163] 5. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 4 above, further comprising the steps of: heating a sulfur source at 200° C. to 450° C. outside the heating furnace to obtain a gas containing sulfur element;

[0164] The gas containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

[0165] 6. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 5 above, wherein a solid containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

[0166] 7. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 6 above, wherein the heating temperature in the heating and melting is 600°C to 900°C.

[0167] 8. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 7 above, wherein the water dew point of the gas atmosphere separated from the first space in the heating furnace is lower than -30°C.

[0168] 9. The method for producing a sulfide-based solid electrolyte according to any one of 1 to 8 above, wherein the oxygen concentration of the gas atmosphere separated from the first space in the heating furnace is less than 100 ppm.

[0169] 10. A manufacturing apparatus for a sulfide-based solid electrolyte, comprising a heating furnace for heating and melting a raw material,

[0170] The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside of the heating furnace with the outside.

[0171] The partition separates the melt formed by heating and melting the raw material in the heating furnace and the gap between the heating furnace into a first space where the sulfur supply unit is located and a second space where the other structures are located.

[0172] The sulfur supply unit forms a sulfur-excess atmosphere by introducing a component containing sulfur element into the first space.

[0173] 11. The apparatus for producing a sulfide-based solid electrolyte according to 10 above, wherein the other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

[0174] In the above, various embodiments are described with reference to the accompanying drawings, but the present invention is certainly not limited to the above examples. It can be understood that for those skilled in the art, various variations or modifications can be thought of within the scope of the scope of the patent claim, and these certainly also belong to the technical scope of the present invention. In addition, the various constituent elements in the above embodiments can also be arbitrarily combined within the scope of the invention without departing from the main purpose of the invention.

[0175] It should be noted that the present application is based on Japanese patent application (Japanese Patent Application No. 2022-081848) filed on May 18, 2022, and the contents thereof are incorporated herein by reference.

[0176] Explanation of symbols

[0177] 100 Manufacturing Devices

[0178] 10Heating furnace

[0179] 11Raw material input department

[0180] 13Sulfur supply unit

[0181] 15Sulfide solid electrolyte discharge unit

[0182] 19, 19a, 19b separator

[0183] 21, 21a, 21b Gas atmosphere section

[0184] 23 Sulfur Excess Atmosphere Section

[0185] 5 Melt

Claims

1. A method for producing a sulfide-based solid electrolyte, comprising heating and melting a raw material in a heating furnace, The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside and the outside of the heating furnace. The raw materials are heated and melted to form a melt. The partitioning portion separates the gap between the melt and the heating furnace into a first space where the sulfur supplying portion is located and a second space where the other structures are located. A sulfur-excess atmosphere portion is formed by introducing a component containing sulfur element from the sulfur supply portion into the first space.

2. The method for producing a sulfide-based solid electrolyte according to claim 1, wherein: The other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

3. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: The minimum temperature of the second space is 450° C. or lower.

4. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: The step further includes: in a state where the sulfur-excess atmosphere portion is provided in the heating furnace, communicating the interior and the exterior of the heating furnace through at least one of the other structures; The second space includes another structure that allows the inside and the outside of the heating furnace to communicate with each other.

5. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: The method further comprises the following steps: heating a sulfur source at 200° C. to 450° C. outside the heating furnace to obtain a gas containing sulfur element; The gas containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

6. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: A solid containing elemental sulfur is introduced from the sulfur supply unit as the component containing elemental sulfur.

7. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: The heating temperature in the heating and melting is 600°C to 900°C.

8. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: In the heating furnace, a moisture dew point of the gas atmosphere separated from the first space is lower than -30°C.

9. The method for producing a sulfide-based solid electrolyte according to claim 1 or 2, wherein: In the heating furnace, the oxygen concentration of the gas atmosphere separated from the first space is less than 100 ppm.

10. A manufacturing apparatus for a sulfide-based solid electrolyte, comprising a heating furnace for heating and melting a raw material, The heating furnace includes: a sulfur supply unit, a partition provided inside the heating furnace, and one or more other structures that can connect the inside and the outside of the heating furnace. The partition separates the melt formed by heating and melting the raw material in the heating furnace and the gap of the heating furnace into a first space where the sulfur supply unit is located and a second space where the other structure is located. The sulfur supply unit forms a sulfur-excess atmosphere unit by introducing a component containing sulfur element into the first space.

11. The manufacturing apparatus of the sulfide-based solid electrolyte according to claim 10, wherein: The other structure is at least one of a raw material input portion and a sulfide-based solid electrolyte discharge portion.

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