Method and apparatus for producing lithium sulfide

Abstract

The present invention addresses the problem of providing a method for producing lithium sulfide capable of increasing the degree of freedom in designing a stirring device for a lithium raw material and efficiently delivering a sulfur-containing gas to the entire lithium raw material. In the method for producing lithium sulfide according to the present invention, a solid lithium raw material is stirred by a rotatable stirring device while blowing a sulfur-containing gas through a gas blow-out port provided in the stirring device and bringing the gas into contact with the lithium raw material to produce lithium sulfide. The lithium raw material is preferably stirred by the stirring device in a state in which a certain amount of the lithium raw material is charged into a reaction container. It is also preferable to stir the lithium raw material by the stirring device while conveying the lithium raw material in one direction.

Description

Lithium sulfide manufacturing method and manufacturing apparatus

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

[0002] Lithium sulfide has generally been produced by reacting hydrogen sulfide with a lithium source compound. For example, Patent Documents 1 and 2 describe a method for producing lithium sulfide by reacting lithium hydroxide, a lithium source, with hydrogen sulfide under heating. These documents propose ways to prevent the raw material lithium hydroxide particles from caking together and the product lithium sulfide from adhering to the walls of a reactor.

[0003] Specifically, in Patent Document 1, lithium hydroxide is charged into a reaction vessel, and the temperature of the inner wall of the reaction vessel that is in contact with the lithium hydroxide is maintained at 140 to 230°C, the temperature of the lid of the reaction vessel is maintained at 100°C or higher, and the lithium hydroxide and hydrogen sulfide gas are reacted while stirring so as not to retain the lithium hydroxide.

[0004] In Patent Document 2, lithium hydroxide is sealed in a reaction vessel, and the reaction vessel is vibrated from the outside to move the lithium hydroxide, thereby causing the lithium hydroxide to react with hydrogen sulfide gas.

[0005] US2017 / 0368515A1WO2023 / 195418A1

[0006] In the technology described in Patent Document 1, a hydrogen sulfide gas supply pipe is installed in lithium hydroxide charged in a reaction vessel, and the open end of the supply pipe is buried in the lithium hydroxide. Therefore, it is necessary to use a stirring device with a shape that does not interfere with stirring of the lithium hydroxide, or to adjust the installation position of the stirring device.

[0007] In the technology described in Patent Document 2, hydrogen sulfide gas is supplied to the space within a reaction vessel, and hydrogen sulfide gas is not supplied directly into lithium hydroxide. Therefore, even though the lithium hydroxide is vibrated to keep it moving, it cannot be said that the lithium hydroxide and hydrogen sulfide gas are sufficiently mixed, and the reaction takes time.

[0008] Therefore, an object of the present invention is to provide a method and apparatus for producing lithium sulfide that can overcome the various drawbacks of the prior art described above.

[0009] The present invention provides a method for producing lithium sulfide, which comprises stirring a solid lithium raw material with a rotatable stirring device while blowing a sulfur-containing gas through a gas outlet provided in the stirring device to bring the sulfur-containing gas into contact with the lithium raw material, thereby generating lithium sulfide.

[0010] The present invention provides an apparatus for producing lithium sulfide, comprising: a reaction vessel into which a solid lithium raw material is charged; and an agitating blade installed in the reaction vessel, wherein the agitating blade has an outlet for a sulfur-containing gas.

[0011] The present invention provides an apparatus for producing lithium sulfide, the apparatus comprising a conveying device having a cylinder and a screw installed in the cylinder, the conveying device being capable of conveying a solid lithium raw material in one direction by rotation of the screw about its axis, wherein the screw has an outlet for a sulfur-containing gas.

[0012] Furthermore, the present invention provides an apparatus for producing lithium sulfide, which has a cylinder that can rotate around a central axis, and the rotation of the cylinder enables stirring of a solid lithium raw material supplied to the interior of the cylinder, and the apparatus for producing lithium sulfide has an outlet on the circumferential surface of the cylinder that can supply a sulfur-containing gas toward the interior of the cylinder.

[0013] Fig. 1 is a cross-sectional view schematically showing a lithium sulfide production apparatus used in a step in the production method of the present invention. Figures 2(a) to 2(d) are each a schematic view showing another embodiment of a stirring device in the production apparatus shown in Fig. 1. Fig. 3 is a cross-sectional view schematically showing another lithium sulfide production apparatus used in a step in the production method of the present invention. Fig. 4 is a partially cutaway perspective view schematically showing yet another lithium sulfide production apparatus used in a step in the production method of the present invention.

[0014] The present invention will be described below based on preferred embodiments with reference to the drawings. Fig. 1 shows a schematic cross-sectional structure of a lithium sulfide production apparatus 10 used in the production method of the present invention. The production apparatus 10 shown in the figure is capable of producing lithium sulfide by stirring a solid lithium raw material with a rotatable stirring device while blowing a sulfur-containing gas through a gas outlet provided in the stirring device to bring the gas into contact with the lithium raw material. For this purpose, the production apparatus 10 shown in the figure has a reaction vessel 20 capable of heating the lithium sulfide raw material under sealed conditions, and a stirring device 40 housed in the space within the reaction vessel 20.

[0015] The reaction vessel 20 includes a cylindrical main body 23 having an open top and a closed bottom, and a lid 24 disposed on top of the main body 23. The interior of the main body 23 is hollow and can accommodate a lithium source material. The main body 23 is divided into an upper region 23a and a lower region 23b. The upper region 23a of the main body 23 is cylindrical. On the other hand, the lower region 23b has a curved surface that protrudes downward, such as an inverted cone or hemisphere, and its diameter decreases toward the bottom. An outlet (not shown) is provided at the bottom of the lower region 23b for removing the produced lithium sulfide to the outside. A heating device 26 is installed on the outer surface of the main body 23, enabling heating of the lithium source material accommodated inside the main body 23. The heating device 26 is installed from the upper region 23a to the lower region 23b of the main body 23. There are no particular limitations on the heating device 26, and for example, an electric heater or a heating medium such as steam can be used.

[0016] The lid 24 is shaped to cover the opening of the main body 23, thereby sealing the interior of the main body 23. A support 32 is installed on the top surface of the lid 24. The support 32 supports a rotating shaft 31 that hangs down from the top surface of the lid 24. A drive motor (not shown) is disposed within the support 32. The drive motor is connected to the upper end region of the rotating shaft 31, allowing the rotating shaft 31 to rotate in both forward and reverse directions around its axis. The rotating shaft 31 hangs down from the top surface of the lid 24 and extends into the interior of the main body 23.

[0017] An agitator 40 is attached to the lower end region of the rotating shaft 31. The agitator 40 is an agitator blade composed of a rotating shaft portion 41 and a blade portion 42. The rotating shaft portion 41 of the agitator 40 is connected to the rotating shaft 31. The rotating shaft portion 41 extends in the same direction as the rotating shaft 31. The agitator 40 can rotate in both forward and reverse directions as the rotating shaft 31 rotates.

[0018] The wing portions 42 are attached to the lower end region of the rotating shaft portion 41 so as to intersect with, for example, be perpendicular to, the rotating shaft portion 41. The wing portions 42 are attached so as to be located at or near the boundary between the upper region 23a and the lower region 23b in the height direction of the main body portion 23. The overall length of the wing portions 42 is adjusted so that clearances are generated between the left and right side edges of the wing portions 42 and the inner wall of the main body portion 23.

[0019] The rotating shaft portion 41 and the blade portion 42 of the agitator 40 are both formed of hollow bodies, such as pipes. The rotating shaft 31 connected to the agitator 40 is also formed of a hollow body such as a pipe. The cross section of these pipes may be, for example, circular, elliptical, or oval. The interior of the section from the rotating shaft 31 to the agitator 40 forms a single space. The left and right side edges of the blade portion 42 of the agitator 40 may or may not be open.

[0020] The upper end of the rotating shaft 31 is open (not shown). A supply hose 33 for a sulfur-containing gas is connected to the opening via a joint (not shown) having a known structure. The tip of the supply hose 33 is connected to a supply source (not shown) of the sulfur-containing gas. Connecting the rotating shaft 31 and the supply hose 33 via the joint makes it possible to rotate the rotating shaft 31 in both forward and reverse directions without rotating the supply hose 33.

[0021] One or more openings are independently formed in the rotating shaft portion 41 and the blade portion 42 of the agitator 40. In the embodiment shown in FIG. 1, a plurality of first openings 41a are formed in the rotating shaft portion 41, and a plurality of second openings 42a are formed in the blade portion 42. When sulfur-containing gas is supplied through the sulfur-containing gas supply hose 33 described above, the sulfur-containing gas passes through the internal space of the rotating shaft 31, reaches the internal space of the agitator 40, and is blown into the inside of the main body 23 through the first opening 41a and the second opening 42a. That is, the agitator 40 (which is an agitator blade in this embodiment) has sulfur-containing gas outlets 41a, 42a.

[0022] Next, a method for producing lithium sulfide using the production apparatus 10 having the above configuration will be described. First, the lid 24 of the reaction vessel 20 is opened to expose the inside of the main body 23. Then, a lithium raw material is charged into the main body 23. It is preferable that the lithium raw material is charged into the main body 23 in a solid state. The term "solid lithium raw material" is intended to exclude lithium raw material in an aqueous solution state. Therefore, lithium raw material that has absorbed water contained in the air is included in the category of solid lithium raw material. Note that instead of opening the lid 24 to charge the lithium raw material into the main body 23, an inlet for charging the lithium raw material may be provided in the lid 24.

[0023] As the lithium raw material, any compound capable of producing lithium sulfide upon reaction with a sulfur-containing gas can be used without particular limitation. For example, lithium hydroxide, lithium carbonate, lithium sulfide, lithium oxide, etc. can be used, but are not limited to these. It is known that lithium hydroxide exists in an anhydrous form and a hydrate form. The lithium hydroxide used in the present production method may be either an anhydrous form or a hydrate form, as long as it is a solid.

[0024] When lithium hydroxide, particularly a hydrate of lithium hydroxide, is used as the lithium raw material, water is generated by the sulfurization reaction, and the generated water may cause solidification of the lithium hydroxide raw material and the lithium sulfide product, but the present production method can effectively prevent such solidification, and is therefore particularly effective when a hydrate of lithium hydroxide is used as the lithium raw material.

[0025] The lithium raw material is generally in the form of a powder. There is no particular limitation on the particle size of the lithium raw material. In the present production method, lithium sulfide is produced by a solid-state reaction, so from the viewpoint of enhancing reactivity, the volume cumulative particle size D of the lithium raw material at a cumulative volume of 50% by volume measured by a laser diffraction / scattering particle size distribution measurement method is set to 1. ５０ is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less. ５０ is, for example, preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 100 μm or more.

[0026] When charging the lithium source material into the main body 23, it is preferable to charge an amount of the lithium source material such that the rotating shaft portion 41 and the blade portion 42 of the stirring device 40 are buried in the lithium source material, from the viewpoint of efficiently producing lithium sulfide.

[0027] After a certain amount of lithium source material is charged into the main body 23, the top of the main body 23 is closed with the lid 24, and the inside of the reaction vessel 20 is sealed. Next, the stirring device 40 is rotated to stir the lithium source material. Then, the inside of the reaction vessel 20 is heated by the heating device 26. The heating temperature is preferably, for example, 100°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher. On the other hand, the heating temperature is preferably, for example, 450°C or lower, and particularly preferably 300°C or lower.

[0028] While the inside of the reaction vessel 20 is heated to a predetermined temperature and the lithium raw material is stirred, the sulfur-containing gas is blown into the reaction vessel 20 through the first opening 41 a and the second opening 42 a provided in the stirring device 40, and the sulfur-containing gas and the lithium raw material are brought into contact with each other. The contact between the two causes sulfurization of the lithium raw material, resulting in lithium sulfide (Li ２ As described above, in this production method, a fixed amount of lithium raw material is charged and sulfurized, so this production method can be said to be a batch method. In addition, this production method can be said to be a dry method because it is a reaction between a solid lithium raw material and a sulfur-containing gas.

[0029] It is preferable that the agitator 40 rotates continuously while the sulfur-containing gas is being blown into the lithium raw material through the first opening 41 a and the second opening 42 a. The rotation speed of the agitator 40 can be appropriately adjusted depending on the volume of the reaction vessel 20, the amount of the lithium raw material charged, the dimensions of the agitator 40, etc. The unreacted sulfur-containing gas is discharged to the outside of the reaction vessel 20 through the exhaust gas pipe 34 attached to the lid 24. It is preferable that the discharged unreacted sulfur-containing gas is completely burned using a burner or the like, and then neutralized with a sodium hydroxide solution to be treated as sodium sulfate or the like.

[0030] The sulfur-containing gas to be blown into the reaction vessel 20 is, for example, hydrogen sulfide gas (H ２ S), carbon disulfide gas (CS ２ ), sulfur oxides (SO Ｘ and sulfur gas obtained by heating solid sulfur (S) to a boiling point or higher to vaporize it. These sulfur-containing gases may be used alone or in combination of two or more.

[0031] The concentration of the sulfur-containing gas supplied into the reaction vessel 20 is preferably 10 vol% or more and 100 vol% or less. A sulfur-containing gas concentration of 100 vol% means a gas consisting only of sulfur-containing gas, i.e., a pure gas. When the sulfur-containing gas concentration is less than 100 vol%, the gas supplied into the reaction vessel 20 is a mixed gas of sulfur-containing gas and an inert gas such as argon or nitrogen or a reducing gas such as hydrogen. If the sulfur-containing gas concentration is 10 vol% or more, the contact reaction between the sulfur-containing gas and the lithium raw material occurs sufficiently, lithium sulfide can be efficiently produced, and unreacted lithium raw material can be prevented from remaining. From this viewpoint, the concentration of the sulfur-containing gas supplied into the reaction vessel 20 can be 50 vol% or more and 100 vol% or less, may be 50 vol% or more and 90 vol% or less, or may be 60 vol% or more and 80 vol% or less.

[0032] According to this production method, the sulfur-containing gas is directly injected into the lithium raw material charged in the reaction vessel 20, which has the advantage that the sulfur-containing gas is quickly and thoroughly distributed throughout the lithium raw material, thereby improving the efficiency of lithium sulfide production. Furthermore, since the agitator 40 continues to rotate while the sulfur-containing gas is being injected, the lithium raw material and the product lithium sulfide are less likely to adhere to the periphery of the first opening 41 a and the second opening 42 a, which are the sulfur-containing gas outlets provided in the agitator 40, which has the advantage that reaction interference due to adhesion of these substances is less likely to occur. Furthermore, according to this production method, there is no need to install a sulfur-containing gas inlet pipe in the reaction vessel 20 separately from the agitator 40, and there is no interference between the inlet pipe and the agitator 40, which has the advantage of increasing the degree of freedom in designing the agitator 40.

[0033] In this embodiment, sulfur-containing gas is blown out from both the rotating shaft portion 41 and the blade portion 42 of the stirring device 40, but the manner in which the sulfur-containing gas is blown out is not limited to this, and it is sufficient that the sulfur-containing gas is blown out from at least one of the rotating shaft portion 41 and the blade portion 42.

[0034] 2(a) to (d) show another embodiment of the stirring impeller as a rotatable stirring device 40. The stirring device 40 of the embodiment shown in FIG. 2(a) consists of a stirring impeller having an anchor blade as the rotating shaft portion 41 and the blade portion 42. The stirring device 40 of the embodiment shown in FIG. 2(b) consists of a stirring impeller having a helical ribbon blade as the rotating shaft portion 41 and the blade portion 42. The stirring device 40 of the embodiment shown in FIG. 2(c) consists of a stirring impeller having a screw blade as the rotating shaft portion 41 and the blade portion 42. The stirring device 40 of the embodiment shown in FIG. 2(d) consists of a stirring impeller having a propeller blade as the rotating shaft portion 41 and the blade portion 42. In any of the embodiments shown in these figures, a sulfur-containing gas outlet is provided at some position on the stirring impeller. When using the stirring device 40 of the embodiment shown in FIGS. 2(a) to (d), the same effects as the embodiment shown in FIG. 1 are achieved.

[0035] Next, another embodiment of the present invention will be described with reference to FIG. 3 . The embodiment shown in FIG. 3 will be described mainly with respect to differences from the previously described embodiment shown in FIG. 1 , and the description of the embodiment shown in FIG. 1 applies to points not specifically described. The lithium sulfide production apparatus 10 shown in FIG. 3 includes a cylinder 12 extending in one direction X and a screw 11 disposed within the cylinder 12. The cylinder 12 is made of a material inactive to the lithium sulfide production reaction, such as a metal or ceramic. Like the cylinder 12, the screw 11 is also made of a material inactive to the lithium sulfide production reaction, such as a metal or ceramic. A spiral groove extending along the length of the screw 11 is formed on the surface of the screw 11. A drive motor 16 is connected to the rear end of the screw 11, thereby enabling the screw 11 to rotate in both forward and reverse directions around its axis. The rotation of the screw 11 around its axis transports the solid lithium material in one direction. That is, the screw 11 functions as a transport device capable of transporting the solid lithium material in one direction. The screw 11 also functions as a stirring device that can rotate in both forward and reverse directions to stir the solid lithium raw material. Therefore, in this production method, the lithium raw material sulfur-containing gas, which is the reactant, is continuously supplied. In other words, this production method is a continuous method. Producing lithium sulfide by a continuous method is advantageous from the viewpoint of increasing the production efficiency of lithium sulfide compared to a batch method. Furthermore, since this production method involves a reaction between a solid lithium raw material and a sulfur-containing gas, it can be said to be a dry method similar to the embodiment shown in FIG. 1.

[0036] The manufacturing apparatus 10 is provided with a hopper 13 near an upstream end 12a of the cylinder 12 for supplying the lithium raw material into the cylinder 12. The hopper 13 is connected to the cylinder 12 via a supply pipe 13a, and is capable of supplying the lithium raw material into the cylinder 12.

[0037] The production apparatus 10 is provided with a recovery tank 14 that removes and recovers lithium sulfide produced by the reaction from the reaction system, near the downstream end 12b of the cylinder 12. The recovery tank 14 is connected to the cylinder 12 via a discharge pipe 14a, so that the produced lithium sulfide can be removed from inside the cylinder 12 to the recovery tank 14.

[0038] The manufacturing apparatus 10 includes a heating device 15 capable of heating at least a portion of the cylinder 12. The heating device 15 is attached to the outer surface of the cylinder 12 so as to cover a portion of the cylinder 12. Specifically, the heating device 15 is disposed in a heating zone 12C located between an upstream zone 12A including the upstream end 12a of the cylinder 12 and a downstream zone 12B including the downstream end 12b. The heating zone 12C is directly heated by the heating device 15. Meanwhile, the upstream zone 12A and the downstream zone 12B located upstream and downstream of the heating zone 12C, respectively, are not directly heated by the heating device 15 but are indirectly heated by heat conduction from the heating zone 12C. The type of the heating device 15 is not particularly limited as long as it is capable of heating the cylinder 12, and any device with a structure known in the art can be used. For example, an electric heater can be used as the heating device 15.

[0039] A hollow portion (not shown) extending along the axial direction of the screw 11 is formed inside the screw 11. The hollow portion is open at the rear end of the screw 11. A supply hose 17 for a sulfur-containing gas is connected to the opening via a joint (not shown) having a known structure. The tip of the supply hose 17 is connected to a supply source (not shown) of the sulfur-containing gas. By connecting the screw 11 and the supply hose 17 via the joint, it is possible to rotate the screw 11 in both forward and reverse directions without rotating the supply hose 17.

[0040] One or more openings are formed on the circumferential surface of the screw 11. In the embodiment shown in Fig. 3, a state in which a plurality of openings 11a are regularly formed on the circumferential surface of the screw 11 is shown. The openings 11a are preferably formed as spiral grooves. The openings 11a communicate with a hollow portion formed in the screw 11. When a sulfur-containing gas is supplied through the sulfur-containing gas supply hose 17 described above, the sulfur-containing gas reaches the openings 11a through the hollow portion of the screw 11 and is blown into the inside of the cylinder 12 through the openings 11a. That is, the screw 11 has an outlet 11a for the sulfur-containing gas.

[0041] Next, a method for producing lithium sulfide using the production apparatus 10 having the above configuration will be described. First, a sulfur-containing gas is supplied from the opening 11a of the screw 11 toward the space inside the cylinder 12 provided in the production apparatus 10. This causes the space inside the cylinder 12 to be filled with the sulfur-containing gas.

[0042] Once the sulfur-containing gas has sufficiently spread throughout the space in the cylinder 12, the heating device 15 is operated to heat the space. The heating temperature can be set to a temperature at which the lithium sulfide production reaction proceeds smoothly. Alternatively, the heating device 15 may be operated to heat the space, and then the sulfur-containing gas may be supplied into the space.

[0043] When the temperature inside the space of the cylinder 12 reaches the set temperature, the supply pipe 13a connecting the hopper 13 and the cylinder 12 is opened, and the lithium raw material stored in the hopper 13 is continuously supplied into the cylinder 12. This allows the lithium raw material to be continuously transported into the cylinder 12. The lithium raw material is transported through the space inside the cylinder 12 from upstream to downstream along the X direction in FIG. 3 .

[0044] The lithium raw material is transported in one direction by the rotation of the screw 11. While being transported in one direction, the lithium raw material is stirred by the rotation of the screw 11. Under this stirring state, a sulfur-containing gas is blown into the space within the cylinder 12 through the sulfur-containing gas outlet 11a provided on the screw 11, and the lithium raw material and the sulfur-containing gas come into contact with each other. In this way, the target lithium sulfide is produced. The produced lithium sulfide is transported downstream by the rotation of the screw 11 and recovered in the recovery tank 14. Note that the unreacted sulfur-containing gas is discharged outside the reaction system through the exhaust gas pipe 19 provided in the middle of the discharge pipe 14a connecting the downstream end 12b of the cylinder 12 and the recovery tank 14. The method for treating the discharged unreacted sulfur-containing gas is as described above.

[0045] According to this production method, the sulfur-containing gas is blown directly into the lithium raw material continuously supplied to the space in the cylinder 12, so that the sulfur-containing gas quickly and thoroughly spreads throughout the lithium raw material, and the continuous process has the advantage of significantly improving the efficiency of lithium sulfide production. Furthermore, since the screw 11 continues to rotate while the sulfur-containing gas is being blown in, the lithium raw material and the product lithium sulfide are less likely to adhere to the periphery of the sulfur-containing gas outlet 11a provided on the screw 11, which has the advantage of making it less likely for the reaction to be hindered by the adhesion of these substances. Furthermore, according to this production method, there is no need to install a sulfur-containing gas inlet pipe in the cylinder 12 separately from the screw 11, and there is no interference between the inlet pipe and the screw 11, which has the advantage of increasing the design freedom of the screw 11 and the cylinder 12.

[0046] FIG. 4 shows a manufacturing apparatus 10 according to another embodiment of the present invention. The manufacturing apparatus 10 shown in the figure has a cylindrical body 50. The cylindrical body 50 is rotatable in both forward and reverse directions around its central axis L. For this purpose, the cylindrical body 50 is connected to a drive source (not shown) such as a motor. The interior of the cylindrical body 50, which is the reaction space, is heated to a predetermined temperature, and then a sulfur-containing gas is supplied toward the interior of the cylindrical body 50. For this purpose, the cylindrical body 50 has, on its circumferential surface, an outlet 51 that penetrates the thickness direction of the cylindrical body 50 and can supply the sulfur-containing gas. There is no particular limitation on the number of outlets 51 provided in the cylindrical body 50. As long as a sufficient amount of sulfur-containing gas can be supplied toward the interior of the cylindrical body 50, there may be one outlet 51 or two or more outlets 51. FIG. 4 shows a state in which a plurality of outlets 51 are provided in the cylindrical body 50.

[0047] Next, a solid lithium source material is supplied into the cylindrical body 50. After or while the lithium source material is being supplied, the cylindrical body 50 is rotated around its central axis L to agitate the lithium source material. The lithium source material may be supplied continuously or batchwise.

[0048] With the sulfur-containing gas supplied to the inside of the cylinder 50, the lithium raw material is stirred by the cylinder 50, whereby the sulfur-containing gas and the lithium raw material come into contact with each other. In this way, the target lithium sulfide is produced.

[0049] From the viewpoint of ensuring more reliable stirring of the lithium source material by the cylinder 50, the cylinder 50 preferably has a baffle plate 52 erected from the inner surface 50a of the cylinder 50 toward the center of the cylinder 50. The baffle plate 52 extends along the direction of the central axis L of the cylinder 50. While FIG. 4 shows a state in which one baffle plate 52 is provided on the inner surface of the cylinder 50, the number of baffles 52 is not limited to this, and two or more baffles may be provided. When a plurality of baffles 52 are used, the baffles 52 can be provided at predetermined intervals along the circumferential direction of the cylinder 50.

[0050] 4, the baffle plate 52 may be provided with one or more through holes 53 penetrating through the baffle plate 52 in the thickness direction. By providing the through holes 53 in the baffle plate 52, the lithium source can be stirred more efficiently, and the lithium source can be brought into contact with the sulfur-containing gas more efficiently.

[0051] The lithium sulfide produced by each of the above methods can be subjected to a pulverization step and a sieving step as post-treatments to form a powder having an appropriate particle size distribution.

[0052] The lithium sulfide produced by each of the above methods is useful as a raw material for the sulfide solid electrolyte of a lithium ion battery. For example, lithium sulfide and diphosphorus pentasulfide (P ２ S ５ ) or other sulfides by mechanical milling reaction to obtain, for example, Li ７ P ３ S １１ and LiPS ４ Alternatively, a crystalline solid electrolyte, for example, a solid electrolyte having a crystal phase with an argyrodite crystal structure, can be synthesized by firing a mixture of lithium sulfide, diphosphorus pentasulfide, and a lithium halide such as lithium chloride (LiCl) and / or lithium bromide (LiBr) under an inert gas atmosphere or a hydrogen sulfide atmosphere. The substance to be reacted with lithium sulfide to synthesize the solid electrolyte is not particularly limited. For example, in addition to the above-mentioned diphosphorus pentasulfide, silicon sulfide (SiS ２ ), germanium sulfide (GeS ２ ) etc.

[0053] In relation to the above-described embodiments, the present invention further discloses the following lithium sulfide manufacturing method and lithium sulfide manufacturing apparatus. [1] A lithium sulfide manufacturing method comprising: stirring a solid lithium raw material with a rotatable stirring device; blowing a sulfur-containing gas through a gas outlet provided in the stirring device to bring the lithium raw material into contact with the lithium raw material, thereby producing lithium sulfide. [2] The manufacturing method according to [1], in which a certain amount of the lithium raw material is charged into a reaction vessel and the lithium raw material is stirred by the stirring device. [3] The manufacturing method according to [2], in which the stirring device is a stirring blade, and the sulfur-containing gas is blown through the gas outlet provided in at least one of the blade portion and the rotating shaft portion of the stirring blade. [4] The manufacturing method according to [1], in which the lithium raw material is stirred by the stirring device while being transported in one direction. [5] The manufacturing method according to [4], in which the lithium raw material is transported in one direction by a transport device including a cylinder and a screw installed in the cylinder, and the sulfur-containing gas is blown through the gas outlet provided in the screw. [6] An apparatus for producing lithium sulfide, comprising: a reaction vessel for charging a solid lithium source material; and an agitating blade installed in the reaction vessel, wherein the agitating blade has an outlet for a sulfur-containing gas. [7] An apparatus for producing lithium sulfide, comprising: a cylinder and a screw installed in the cylinder, and a conveying device capable of conveying a solid lithium source material in one direction by rotation of the screw about its axis, wherein the screw has an outlet for a sulfur-containing gas. [8] An apparatus for producing lithium sulfide, comprising: a cylindrical body rotatable about its central axis, and wherein the rotation of the cylinder enables stirring of a solid lithium source material supplied inside the cylinder, wherein the cylindrical body has an outlet on its circumferential surface through which a sulfur-containing gas can be supplied toward the inside of the cylinder. [9] The apparatus for producing lithium sulfide according to [8], wherein the cylinder has a baffle plate installed upright from its inner surface toward the center of the cylinder.

[0054] As described above in detail, according to the present invention, there is no need to provide an outlet for a sulfur-containing gas in an apparatus for producing lithium sulfide, which increases the degree of freedom in designing an agitator for the lithium raw material, and also makes it possible to efficiently distribute the sulfur-containing gas throughout the lithium raw material.

Claims

1. A method for producing lithium sulfide, comprising: stirring a solid lithium raw material with a rotatable stirring device; blowing a sulfur-containing gas into the lithium raw material through a gas outlet provided in the stirring device; and bringing the sulfur-containing gas into contact with the lithium raw material to produce lithium sulfide.

2. The manufacturing method according to claim 1, wherein the lithium raw material is stirred by the stirring device in a state where a certain amount of the lithium raw material is charged into a reaction vessel.

3. The manufacturing method according to claim 2, wherein the stirring device is a stirring blade, and the sulfur-containing gas is blown in through the gas outlet provided in at least one of the blade portion and the rotating shaft portion of the stirring blade.

4. The method according to claim 1, wherein the lithium raw material is stirred by the stirring device while being conveyed in one direction.

5. The manufacturing method described in claim 4, wherein the lithium raw material is transported in one direction by a transport device having a cylinder and a screw installed in the cylinder, while the sulfur-containing gas is blown in through the gas outlet provided on the screw.

6. An apparatus for producing lithium sulfide, comprising: a reaction vessel into which a solid lithium raw material is charged; and an agitating blade installed in the reaction vessel, wherein the agitating blade has an outlet for a sulfur-containing gas.

7. An apparatus for producing lithium sulfide, comprising a conveying device having a cylinder and a screw installed in the cylinder, capable of conveying a solid lithium raw material in one direction by rotation of the screw about its axis, wherein the screw has an outlet for a sulfur-containing gas.

8. An apparatus for producing lithium sulfide, which has a cylindrical body that can rotate around a central axis, and which is capable of stirring a solid lithium raw material supplied to the interior of the cylinder by the rotation of the cylinder, and which has an outlet on the circumferential surface of the cylinder that can supply a sulfur-containing gas toward the interior of the cylinder.

9. The lithium sulfide production apparatus according to claim 8, wherein the cylinder has a baffle plate extending from the inner surface of the cylinder toward the center of the cylinder.

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