Method for preparing lithium sulfide

Abstract

The invention of the present application provides a method for preparing lithium sulfide, comprising: a first raw material preparation step of preparing a first raw material including lithium; a second raw material preparation step of preparing a second raw material including carbon; a first raw material pulverizing step of pulverizing the prepared first raw material; a mixing step of adding the pulverized first raw material and the second raw material to a first solvent to prepare a mixture; a first evaporation step of evaporating the solvent from the mixture; a heat treatment step of heat-treating the mixture; a washing step of washing the sintered mixture with a second solvent; a second evaporation step of filtering impurities while evaporating the washed mixture; and a plasticizing step of plasticizing the mixture subjected to the second evaporation step.

Description

Method for producing lithium sulfide

[0001] The present invention relates to a method for manufacturing lithium sulfide, and more specifically, to a method for manufacturing lithium sulfide using lithium sulfate without using hydrogen sulfate to ensure low cost and safety.

[0002] The conventional method of manufacturing lithium sulfide involves a chemical reaction using Li2CO3, / R-Li and H2S. During the Li2S synthesis process, a toxic H2S gas storage device and exhaust equipment for control purposes are additionally required. In addition, in the case of unreacted H2S, a process is required to completely burn the substance with a burner, etc., and then neutralize it with a sodium hydroxide solution to treat it as sodium sulfide.

[0003] The above method poses a productivity issue because it requires additional equipment and processes for H2S gas management for Li2S synthesis. Furthermore, since larger quantities of H2S are used in mass production of Li2S, in addition to the basic material costs for the synthesis process, additional costs for equipment setup and maintenance to maintain stability will increase. Therefore, it is judged to be uneconomical as a method for mass production.

[0004] Lithium hydride (LiH), used as a raw material in another conventional lithium sulfide manufacturing method, is more expensive than lithium sulfate (Li2SO4). This technology uses a dry ball milling process for synthesis, making the process simpler compared to other methods. However, the high cost of raw materials makes it less economical when moving to mass production. Furthermore, the purity of the powder synthesized through the milling process is relatively low, requiring an additional purification process.

[0005] Korean Patent Publication No. 10-2022-0161749 relates to a method for producing high-purity lithium sulfide, and discloses a method for producing lithium sulfide, including the steps of mixing lithium sulfate (Li2SO4) and carbon (Carbon, C); and reducing the mixture to obtain lithium sulfide (Li2S).

[0006] Japanese Patent Publication No. 6499513 relates to a method for producing lithium sulfide and a method for producing an inorganic solid electrolyte, and discloses a method for producing lithium sulfide, characterized in that a reducing agent (1) selected from an organic compound having multiple hydroxyl groups and a reducing agent (2) selected from a carbon material are used in combination, the mass conversion mixing ratio of the reducing agent (1) and the reducing agent (2) (reducing agent (1) / {reducing agent (1) / {reducing agent (1)+reducing agent (2)}) is 85 to 96 mass%, the reducing agent (1) is a saccharide, and the reducing agent (2) is a porous carbon material.

[0007] Korean Patent Publication No. 10-2509059 relates to a method for producing lithium sulfide, and discloses a method for producing lithium sulfide, characterized by including the steps of: a) mechanically milling a powder mixture composed of lithium hydroxide (LiOH) and lithium oxide (Li2O) to produce a finely divided powder mixture; and b) reacting the finely divided powder mixture with hydrogen sulfide gas to produce lithium sulfide (Li2S).

[0008] Korean Patent Publication No. 10-2022-0089153 relates to a method for producing lithium sulfide, and discloses a method for producing lithium sulfide, comprising: a first heat treatment step of mixing lithium sulfate and reducing agent powder and heat treating the mixture; a second heat treatment step of heat treating lithium sulfide obtained by reducing lithium sulfate in the first heat treatment step; and a step of obtaining lithium sulfide sublimated in the second heat treatment step.

[0009] Conventional lithium sulfide production technology that does not use hydrogen sulfide may be economical, but a method for producing high-purity lithium sulfide is needed based on safety aspects.

[0010] (Prior art literature)

[0011] (Patent Document)

[0012] Korean Patent Publication No. 10-2022-0161749

[0013] Japanese Patent Publication No. 6499513

[0014] Korean Patent Publication No. 10-2509059

[0015] Korean Patent Publication No. 10-2022-0089153

[0016] The present invention is intended to solve the above-mentioned problem and to provide a method for producing lithium sulfide using a raw material containing lithium and a raw material containing carbon without using hydrogen sulfide.

[0017] In order to achieve these objectives, the present invention provides a method for producing lithium sulfide, comprising a first raw material preparation step of preparing a first raw material including lithium, a second raw material preparation step of preparing a second raw material including carbon, a first raw material crushing step of crushing the prepared first raw material, a mixing step of introducing the crushed first and second raw materials into a first solvent to produce a mixture, a first evaporation step of evaporating the solvent from the mixture, a heat treatment step of heat-treating the mixture, a washing step of washing the sintered mixture with a second solvent, a second evaporation step of filtering out impurities while evaporating the washed mixture, and a calcination step of calcining the mixture that has undergone the second evaporation step.

[0018] Additionally, the first raw material may include at least one of lithium oxide, lithium metal, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isoxate.

[0019] Additionally, the second raw material may include at least one of sugar, alcohol, and carbon-forming material.

[0020] Additionally, the sugar may include at least one of a pentose or a hexose.

[0021] Additionally, the first solvent may include at least one of an ionic liquid, deionized water, purified water, and distilled water.

[0022] Additionally, the second solvent may include at least one of an ionic liquid, ethanol, and acetone.

[0023] Additionally, in the above heat treatment step, the heat treatment temperature may be 500°C to 1200°C.

[0024] Additionally, the mixing ratio of the first raw material and the second raw material may be 2:1 to 6:1 by weight.

[0025] Additionally, in the first raw material crushing step, the first raw material can be crushed to an average particle size of 1 ㎛ to 10 ㎛.

[0026] In addition, a sulfur raw material supply step for additionally supplying sulfur raw material gas during the production of the lithium sulfide may be additionally included.

[0027] Additionally, the sulfur raw material gas supplied in the sulfur raw material supply step may contain at least one of SO, SO2, and SO3.

[0028] In addition, the voltage of the sulfur raw material gas supplied in the above sulfur raw material supply step is 1 atm, and the partial pressure is 1*10 -5 Atmospheric pressure or 1*10 -2 It could be.

[0029] The present invention can also be provided in a form in which various means for solving the above problem are combined.

[0030] As described above, the present invention can achieve low cost and high safety by not using hydrogen sulfide, and can produce high-purity lithium sulfide.

[0031] Figure 1 illustrates a sequence for manufacturing lithium sulfide according to one embodiment of the present invention.

[0032] FIG. 2 illustrates a blade mill, which is one of the crushing means for crushing the first raw material, as an embodiment of the present invention.

[0033] Figure 3 illustrates a blade mill as an embodiment of the present invention.

[0034] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail, so that those with ordinary skill in the art can easily implement the present invention. However, when describing the operating principles of preferred embodiments of the present invention in detail, if a detailed description of a related known function or configuration is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted.

[0035] Additionally, the same drawing reference numerals are used for parts with similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless specifically stated otherwise, but rather implies the inclusion of additional components.

[0036] Additionally, the description that concretizes or adds components may be applied to all inventions unless there are special limitations, and is not limited to the description of a specific invention.

[0037] Additionally, throughout the description and claims of the invention herein, the singular includes the plural unless otherwise stated.

[0038] Additionally, throughout the description and claims of the present invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases of including A, including B, or including A and B.

[0039] The present invention is described in detail with examples according to the drawings.

[0040] FIG. 1 illustrates a sequence for manufacturing lithium sulfide according to one embodiment of the present invention, FIG. 2 illustrates a blade mill, which is one of the crushing means for crushing a first raw material according to one embodiment of the present invention, and FIG. 3 illustrates a blade mill according to one embodiment of the present invention.

[0041] The present invention provides a method for producing lithium sulfide, comprising a first raw material preparation step of preparing a first raw material containing lithium, a second raw material preparation step of preparing a second raw material containing carbon, a first raw material crushing step of crushing the prepared first raw material, a mixing step of introducing the crushed first and second raw materials into a first solvent to produce a mixture, a first evaporation step of evaporating the solvent from the mixture, a heat treatment step of heat-treating the mixture, a washing step of washing the sintered mixture with a second solvent, a second evaporation step of filtering out impurities while evaporating the washed mixture, and a calcination step of calcining the mixture that has undergone the second evaporation step.

[0042] Additionally, the first raw material may include at least one of lithium oxide, lithium metal, lithium salt, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isoxate.

[0043] In addition, in addition to the first raw material described above, a lithium-containing mineral may be additionally used, and the lithium-containing mineral may include at least one of pegmatite, spodumene, petalite, tourmaline (particularly Elbite), and lepidolite.

[0044] In addition, when using the lithium-containing mineral, a first raw material extraction step using a separate refining facility to extract the lithium source may be added.

[0045] In addition, the lithium salt may be at least one of LiTFSI, LiPF6, LiBF4, LiAsF6, LiClO4, LiNO3, (lithium bis(oxalato) borate(LiBOB), LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO3CF3)2, LiC4F9SO3, LiAlCl4, and LiTfO(lithium trifluoromethanesulfonate).

[0046] Additionally, the first raw material may be in either a dried form or a form containing moisture.

[0047] Additionally, the second raw material may include at least one of sugar, alcohol, and carbon-forming material.

[0048] In addition, among the first raw materials, lithium isooxane may be lithium isooxane powder obtained by crushing and sieving a waste lithium isooxane catalyst.

[0049] In addition, the lithium carbonate can be used by producing a lithium chloride solution using the lithium isoxate powder and synthesizing lithium carbonate by adding a sodium carbonate solution dropwise to the lithium chloride solution.

[0050] Additionally, the first raw material crushing step may use a blade mill device as a crushing means.

[0051] In addition, the blade mill device may have a crushing unit at the top for supplying crushing material, a crushing unit including blades for crushing may be located at the bottom of the supply unit, and a discharge unit for discharging crushed material may be located at the bottom of the crushing unit, and the supply unit may be used as a first raw material supply means.

[0052] In addition, the above-mentioned crushing unit may include a rotating impeller in the form of a blade, a motor means for generating and transmitting rotational power, and an external cover means for the outer surface of the impeller.

[0053] Additionally, a liner may be included between the impeller and the external cover means to cushion the impact generated during crushing.

[0054] Additionally, the power generated by the above motor means may be 5 to 50 horsepower.

[0055] In addition, the input surface into which the crushing target is input or the discharge surface from which it is discharged may have a diameter of 50 mm to 150 mm, and the diameters of the input surface or the discharge surface may be formed to be the same or different.

[0056] Additionally, the blade-shaped impeller can rotate at 2,000 RPM to 6,000 RPM.

[0057] In addition, the above impellers may be formed in multiple pieces to improve grinding efficiency.

[0058] In addition, the impeller may be installed to have an inclination of 5°C to 45°C with respect to the central axis, and when the impeller is formed in multiple pieces, it may be formed at the same angle or different angles.

[0059] In addition, a pulverized material storage step for storing the first raw material pulverized through the first raw material pulverization step before mixing may be additionally included, and the pulverized material storage step may selectively supply the pulverized material to the mixing step or the first raw material pulverization step.

[0060] In addition, when the above-mentioned crushed material is supplied to the first raw material crushing step, multiple crushings are performed, so that the particle size can be made smaller, and the efficiency in the mixing step and the purity or yield of the manufactured lithium sulfide can be further increased.

[0061] In addition, for the above-mentioned crushed material storage step, a plurality of storage means may be installed, and the crushed material may be classified and stored according to the particle size of each storage means, and a classification storage step may be additionally included to classify and store the crushed material.

[0062] Additionally, the gap between the outer cover means and the impeller may be 0.5 mm to 20.0 mm, and the narrower the gap, the higher the efficiency.

[0063] Additionally, the carbon molded body may be a porous carbon molded body.

[0064] Additionally, the carbon-forming body may include at least one of activated carbon, coke, graphite, graphene, activated carbon, carbon black, and carbon powder.

[0065] In addition, the carbon-forming body may include activated carbon and may have an average particle diameter of 1 ㎛ or more and 1,500 ㎛ or less.

[0066] Additionally, a preheating step may be additionally included to remove any remaining moisture after the first raw material crushing step, if necessary.

[0067] Additionally, the preheating step may be from 80°C to 350°C.

[0068] Additionally, the sugar may include at least one of a pentose or a hexose.

[0069] Additionally, the pentose may include xylitol.

[0070] Additionally, the hexoses may include sucrose, glucose and fructose.

[0071] Additionally, sorbitol, which is similar to the above hexose, can be used.

[0072] Additionally, the first solvent may include at least one of an ionic liquid, deionized water, purified water, and distilled water.

[0073] Additionally, the second solvent may include at least one of an ionic liquid, ethanol, and acetone.

[0074] In addition, the ionic liquid used in the first solvent or the second solvent is [emim]Cl / AlCl3(emim=ethyl methyl imidazolium), [bmpyr]NTf2(bppyr=butyl methyl pyridinium), [bpy]Br / AlCl3(bpy=4,4'-bipyridine), [choline]Cl / CrCl3O6H2O, [Hpy(CH2)3pyH][NTf2]2(NTf=trifluoromethanesulfonimide), [emim]OTf / [hmim]I(hmim=hexyl methyl imidazolium), [choline]Cl / HOCH2CH2OH, [Et2MeN(CH2CH2OMe)]BF4(Et=ethyl, Me=methyl, Pr=propyl, Bu=butyl, Ph=phenyl, Oct=octyl, Hex=hexyl), [Bu3PCH2CH2C8F 17 ]OTf(OTf=trifluoromethane sulfonate), [bmim]PF6(bmim=butyl methyl imidazolium), [bmim]BF4, [omim]PF6(omim=octyl methyl imidazolium), [Oct3PC 18 H 37]I, [NC(CH2)3mim]NTf2(mim=methyl imidazolium), [Pr4N][B(CN)4], [bmim]NTf2, [bmim]Cl, [bmim][Me(OCH2CH2)2OSO3], [PhCH2mim]OTf, [Me3NCH(Me)CH(OH)Ph] NTf2, [pmim][(HO)2PO2] (pmim = propyl methyl imidazolium), [b(6-Me)quin]NTf2(bquin=butyl quinolinium, [bmim][Cu2Cl3], [C 18 H 37 OCH2mim]BF4(mim = methyl imidazolium), [heim]PF6(heim = hexyl ethyl imidazolium), [mim(CH2CH2O)2CH2CH2mim][NTf2]2(mim=methyl imidazolium), [obim]PF6(obim=octyl butyl imidazolium), [oquin]NTf2(oquin=octyl quinolinium), [hmim][PF3(C2F5)3], [C 14 H 29 mim]Br(mim=methyl imidazolium), [Me2N(C 12 H 25 )2]NO3, [emim]BF4, [mm(3-NO2)im][dinitrotriazolate], [MeN(CH2CH2OH)3], [MeOSO3], [Hex3PC 14 H 29 ]NTf2, [emim][EtOSO3], [choline][ibuprofenate], [emim]NTf2, [emim][(EtO)2PO2], [emim]Cl / CrC l2 , [Hex3PC 14 H 29]N(CN)2, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetraborate ([DEME][BF4]), diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]), dimethylpropylammonium trifluoromethanesulfonate ([dmpa][TfO]), diethylmethylammonium trifluoromethanesulfonylimide ([DEME][TFSI]), and methylpropylpiperidinium trifluoromethanesulfonylimide ([mpp][TFSI]).

[0075] Additionally, as described above, the first solvent may include an imidazole-based ionic liquid, and preferably may be [emim]Cl / AlCl3 (emim=ethyl methyl imidazolium).

[0076] Additionally, the second solvent may include an ammonium-based ionic liquid, more preferably dimethylpropylammonium.

[0077] If the first and second solvents are not added, the production efficiency of lithium sulfide may decrease.

[0078] In addition, the first raw material may be added in an amount of 10 to 50 parts by weight, the second raw material in an amount of 10 to 50 parts by weight, the first solvent in an amount of 50 to 200 parts by weight, and the second solvent in an amount of 50 to 200 parts by weight. If the mixing conditions for the above parts by weight are exceeded, the production efficiency of lithium sulfide may decrease.

[0079] Additionally, the second solvent may have a polarity index of 4.5 to 6.0.

[0080] Additionally, a second solvent extraction step for extracting or removing the second solvent used in the above washing step may be additionally included.

[0081] Additionally, the second solvent may be used by selecting and including at least one of methanol, isopropanol, n-propanol, and tetrahydrofuran.

[0082] Additionally, in the above heat treatment step, the heat treatment temperature may be 500°C to 1,500°C.

[0083] Additionally, the heat treatment temperature may preferably be 700°C or higher.

[0084] Additionally, the mixing ratio of the first raw material and the second raw material may be 2:1 to 6:1 by weight.

[0085] Additionally, in the first raw material crushing step, the first raw material can be crushed to an average particle size of 1 ㎛ to 10 ㎛.

[0086] In addition, a sulfur raw material supply step for additionally supplying sulfur raw material gas during the production of the lithium sulfide may be additionally included.

[0087] Additionally, the sulfur raw material supplied through the above sulfur raw material supply step can be stored in a separate storage means and then supplied.

[0088] Additionally, the above sulfur raw material supply step may be included to increase the purity of the lithium sulfide being manufactured.

[0089] Additionally, the sulfur raw material gas supplied in the sulfur raw material supply step may contain at least one of SO, SO2, and SO3.

[0090] In addition, the voltage of the sulfur raw material gas supplied in the above sulfur raw material supply step is 1 atm, and the partial pressure is 1*10 -5 Atmospheric pressure or 1*10 -2 It could be.

[0091] In addition, a pressure control step for controlling the pressure using a separate exhaust pump for the above partial pressure may be additionally included.

[0092] In addition, the heat treatment step can reach the heat treatment target temperature at a heating rate of 3°C / min to 12°C / min after starting to apply heat.

[0093] Additionally, the heat treatment time of the above heat treatment step may be 30 seconds or longer.

[0094] Additionally, the heat treatment step may be performed under an atmospheric pressure of 1 atm or higher.

[0095] Additionally, the above lithium sulfide production can be carried out in an inert gas atmosphere or a vacuum atmosphere.

[0096] Additionally, an inert gas supply step may be additionally included for the above inert gas atmosphere.

[0097] Additionally, a vacuum stage may be additionally included for the above vacuum atmosphere.

[0098] Additionally, the inert gas may include one or more of argon, nitrogen, neon, methane, carbon monoxide, methane, ethane, propane, butane, and helium.

[0099] Additionally, a drying step may be additionally included after the above-mentioned plasticizing step.

[0100] Additionally, the above drying step may use a separate drying means or natural drying.

[0101] Additionally, the drying step may be performed at a temperature of 60°C or lower.

[0102] In addition, a obtaining step for obtaining lithium sulfide manufactured after the above-mentioned calcination step may be additionally included.

[0103] In addition, in the method for manufacturing the lithium sulfide, resources generated through the first evaporation step, the second evaporation step, the second solvent extraction step, etc. can be recovered and reused within the process.

[0104] Additionally, the resource recovered in the first evaporation step may be a first solvent and may be reused in the mixing step.

[0105] Additionally, the resources recovered in the second evaporation step can be reused in the washing step.

[0106] Additionally, the resources recovered in the second solvent recovery step can be reused in the washing step.

[0107] In addition, the lithium sulfide manufactured above can be utilized in the battery field such as secondary batteries and all-solid-state batteries.

[0108] Additionally, the average size of the manufactured lithium sulfide may be 10㎛ or less.

[0109] Additionally, the purity of the manufactured lithium sulfide may be 99.9% or higher.

[0110] In addition, for the above manufacturing method, a device for manufacturing lithium sulfide can be provided, including a first raw material storage means for storing a first raw material including lithium, a second storage means for storing a second raw material including carbon, a first raw material crushing means for crushing the prepared first raw material, a mixing means for introducing the crushed first and second raw materials into a first solvent to produce a mixture, a first evaporation means for evaporating the solvent from the mixture, a heat treatment means for heat-treating the mixture, a washing means for washing the sintered mixture with a second solvent, a second evaporation means for filtering out impurities while evaporating the washed mixture, and a calcination means for calcining the mixture that has undergone the second evaporation step.

[0111] In addition, the above manufacturing method may additionally include at least one of a sulfur raw material supply means, a preheating means, an inert gas supply means, a vacuum means, a drying means, a first solvent recovery means, and a second solvent recovery means.

[0112] Anyone with ordinary knowledge in the field to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims

1. First raw material preparation step of preparing a first raw material containing lithium; A second raw material preparation step comprising a second raw material containing carbon; A first raw material crushing step for crushing the first raw material prepared above; A mixing step of creating a mixture by adding the above-mentioned crushed first and second raw materials into a first solvent; A first evaporation step of evaporating the solvent from the above mixture; A heat treatment step of heat treating the above mixture; A washing step of washing the above sintered mixture with a second solvent; A second evaporation step for filtering out impurities by evaporating the above-mentioned washed mixture; and A method for producing lithium sulfide, comprising a calcining step of calcining a mixture that has undergone the second evaporation step.

2. In paragraph 1, A method for producing lithium sulfide, wherein the first raw material comprises at least one of lithium oxide, lithium metal, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isoxate.

3. In paragraph 1, A method for producing lithium sulfide, wherein the second raw material comprises at least one of sugar, alcohol, and carbon-forming material.

4. In paragraph 3, A method for producing lithium sulfide, wherein the sugar comprises at least one of a pentose sugar and a hexose sugar.

5. In paragraph 1, A method for producing lithium sulfide, wherein the first solvent comprises at least one of an ionic liquid, deionized water, purified water, and distilled water.

6. In paragraph 1, A method for producing lithium sulfide, wherein the second solvent comprises at least one of an ionic liquid, ethanol, and acetone.

7. In paragraph 1, A method for producing lithium sulfide, wherein the heat treatment temperature in the above heat treatment step is 500°C to 1500°C.

8. In paragraph 1, A method for producing lithium sulfide, wherein the mixing ratio of the first raw material and the second raw material is 2:1 to 6:1 by weight.

9. In paragraph 1, A method for producing lithium sulfide, wherein in the first raw material crushing step, the first raw material is crushed to an average particle size of 1 ㎛ to 10 ㎛.

10. In paragraph 1, A method for producing lithium sulfide, further comprising a sulfur raw material supply step for additionally supplying sulfur raw material gas during the production of the lithium sulfide.

11. In paragraph 10, The sulfur raw material gas supplied in the above sulfur raw material supply stage is SO, SO 2 and SO 3 A method for producing lithium sulfide comprising at least one of the following.

12. In paragraph 10, The voltage of the sulfur raw material gas supplied in the above sulfur raw material supply stage is 1 atm and the partial pressure is 1*10 -5 Pressure or 1*10 -2 A method for producing lithium sulfide.

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