Preparation method of lithium sulfide

Abstract

The present invention provides a method for preparing lithium sulfide, comprising: a first raw material preparation step of preparing a first raw material containing lithium; a second raw material preparation step including a second raw material including carbon; a first raw material crushing step of crushing the prepared first raw material; a mixing step of adding the crushed first raw material and second raw material to a first solvent to generate a mixture; a first evaporation step of evaporating the solvent from the mixture; a heat treatment step of performing heat treatment on 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: plasticizing the mixture subjected to the second evaporation step.

Description

Technical Field

[0001] This invention relates to a method for preparing lithium sulfide, specifically to a method for preparing lithium sulfide without using hydrogen sulfate in order to ensure low cost and safety when using lithium sulfate. Background Technology

[0002] For existing lithium sulfide preparation methods, the process of synthesizing Li2S by utilizing the chemical reaction of Li2CO3 / R-Li and H2S requires additional storage devices for the toxic H2S gas and exhaust equipment for control. For unreacted H2S, it is necessary to completely burn the substance through a burner, neutralize it with sodium hydroxide solution, and then treat it with sodium sulfide.

[0003] The method requires additional equipment for managing H2S gas and involves additional steps to synthesize Li2S, thus causing problems with productivity. Furthermore, the use of larger quantities of H2S in mass production of Li2S incurs additional costs beyond the basic material costs required for the synthesis process, including setup and maintenance costs for maintaining stability. Therefore, it is considered uneconomical as a mass production method.

[0004] For another existing method of lithium sulfide preparation, lithium hydride (LiH) used as a raw material is more expensive than lithium sulfate (Li2SO4). This technology uses a dry ball milling process, which is simpler than other methods, but due to the high price of the basic raw materials, it lacks economic viability for mass production. Furthermore, the purity of the powder synthesized through milling is relatively low, thus requiring additional high-purity refining processes.

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

[0006] Japanese Patent Publication No. 6499513 discloses a method for preparing lithium sulfide and an inorganic solid electrolyte. The method for preparing lithium sulfide is characterized by using a reducing agent (1) selected from organic compounds having multiple hydroxyl groups and a reducing agent (2) selected from carbon materials as reducing agents, wherein the mass conversion ratio of reducing agent (1) to reducing agent (2) (reducing agent (1) / {reducing agent (1) / {reducing agent (1)+reducing agent (2)}) is 85~96% by mass, the reducing agent (1) is a sugar, and the reducing agent (2) is a porous carbon material.

[0007] Korean Patent Publication No. 10-2509059 discloses a method for preparing lithium sulfide, characterized by comprising: a) mechanically grinding a powder mixture composed of lithium hydroxide (LiOH) and lithium oxide (Li2O) to prepare a micronized powder mixture; and b) reacting the micronized powder mixture with hydrogen sulfide gas to prepare lithium sulfide (Li2S).

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

[0009] While conventional lithium sulfide preparation techniques that do not use hydrogen sulfide may be economical, a method for preparing high-purity lithium sulfide is needed due to safety concerns.

[0010] (Existing technical documents)

[0011] (Patent Documents)

[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 Summary of the Invention

[0016] Technical problems to be solved

[0017] In order to solve the above problems, the present invention aims to provide a method for preparing lithium sulfide using lithium-containing raw materials and carbon-containing raw materials without using hydrogen sulfide.

[0018] Technical solution

[0019] To achieve the above objectives, the present invention provides a method for preparing lithium sulfide, comprising: a first raw material preparation step, preparing a first raw material containing lithium; a second raw material preparation step, including a second raw material containing carbon; a first raw material pulverizing step, pulverizing the prepared first raw material; a mixing step, adding the pulverized first and second raw materials to a first solvent to generate a mixture; a first evaporation step, evaporating the solvent from the mixture; a heat treatment step, heat-treating the mixture; a washing step, washing the sintered mixture with a second solvent; a second evaporation step, filtering impurities while evaporating the washed mixture; and a plasticization step, plasticizing the mixture after the second evaporation step.

[0020] In addition, the first raw material may include any one or more of lithium oxide, lithium metal, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isooctanoate.

[0021] In addition, the second raw material may include any one or more of sugar, alcohol and carbon molding.

[0022] In addition, the sugar may include any one or more of pentose or hexose.

[0023] In addition, the first solvent may include any one or more of ionic liquids, deionized water, purified water, and distilled water.

[0024] In addition, the second solvent may include any one or more of ionic liquids, ethanol, and acetone.

[0025] Furthermore, in the heat treatment step, the heat treatment temperature can be from 500°C to 1200°C.

[0026] Furthermore, the mixing ratio of the first raw material and the second raw material can be from 2:1 to 6:1 by weight.

[0027] Furthermore, in the first raw material crushing step, the first raw material can be crushed to an average particle size of 1µm or more and 10µm.

[0028] Furthermore, a sulfur feedstock supply step may be included in the preparation process of the lithium sulfide for additional supply of sulfur feedstock gas.

[0029] Furthermore, the sulfur feedstock gas supplied in the sulfur feedstock supply step may include any one or more of SO, SO2, and SO3.

[0030] Furthermore, the total pressure of the sulfur feedstock gas supplied in the sulfur feedstock supply step is 1 atmosphere, and the partial pressure can be 1×10⁻⁶. -5 Atmospheric pressure up to 1×10 -2 .

[0031] The present invention can also be provided in various combinations of technical solutions to solve the above-mentioned technical problems.

[0032] Technical effect

[0033] As described above, the present invention does not use hydrogen sulfide, thereby achieving low cost and high safety, and can prepare high-purity lithium sulfide. Attached Figure Description

[0034] Figure 1 A process for preparing lithium sulfide according to an embodiment of the present invention is shown.

[0035] Figure 2 A blade mill is shown as one of the crushing components for crushing a first raw material according to an embodiment of the present invention.

[0036] Figure 3 A blade mill according to an embodiment of the present invention is shown. Detailed Implementation

[0037] Hereinafter, embodiments that can be readily implemented by those skilled in the art will be described in detail with reference to the accompanying drawings. However, when describing the working principle of preferred embodiments of the invention in detail, detailed descriptions of related known functions and configurations will be omitted if it is determined that such detailed descriptions may obscure the gist of the invention.

[0038] Furthermore, in all the accompanying drawings, the same reference numerals will be used to denote parts that perform similar functions or operations. Throughout the specification, when describing a connection between one part and another, this includes not only direct connections but also indirect connections where other devices are present in between. Moreover, unless specifically stated otherwise, including a component means including other components, not excluding other components.

[0039] Furthermore, unless otherwise specified, the description of a component, whether limited or detailed, can be applied to all inventions and is not limited to the description of a particular invention.

[0040] Furthermore, in the description of the invention and throughout the claims, unless otherwise stated, the singular form also includes the plural form.

[0041] Furthermore, throughout the description of this invention and the claims, unless otherwise stated, "or" includes "and". Therefore, "including A or B" means three cases: including A, including B, and including both A and B.

[0042] The present invention will be described with reference to the accompanying drawings, as shown in detailed embodiments.

[0043] Figure 1 The preparation process of lithium sulfide according to an embodiment of the present invention is shown. Figure 2 A blade mill, according to an embodiment of the present invention, is shown as one of the pulverizing components for pulverizing a first raw material. Figure 3 A blade mill according to an embodiment of the present invention is shown.

[0044] This invention provides a method for preparing lithium sulfide, comprising: a first raw material preparation step, preparing a first raw material containing lithium; a second raw material preparation step, including a second raw material containing carbon; a first raw material pulverizing step, pulverizing the prepared first raw material; a mixing step, adding the pulverized first and second raw materials to a first solvent to generate a mixture; a first evaporation step, evaporating the solvent from the mixture; a heat treatment step, heat-treating the mixture; a washing step, washing the sintered mixture with a second solvent; a second evaporation step, filtering impurities while evaporating the washed mixture; and a plasticizing step, plasticizing the mixture after the second evaporation step.

[0045] In addition, the first raw material may include any one or more of lithium oxide, lithium metal, lithium salt, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isooctanoate.

[0046] In addition to the first raw material described above, lithium-containing minerals can be further utilized, which may include any one or more of pegmatite, spodumene, petalite, tourmaline (especially elbite), and lepidolite.

[0047] In addition, when using the lithium-containing mineral, a first raw material extraction step can be added, in which a separate purification device is used to extract the lithium source.

[0048] Furthermore, the lithium salt can be any one or more 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 lithium trifluoromethanesulfonate (LiTfO).

[0049] Furthermore, the first raw material can be either in a dry form or in a form containing moisture.

[0050] In addition, the second raw material may include any one or more of sugar, alcohol and carbon molding.

[0051] In addition, the lithium isooctanoate in the first raw material can be lithium isooctanoate powder obtained by crushing and sieving waste lithium isooctanoate catalyst.

[0052] Furthermore, regarding the lithium carbonate, it can be used to generate a lithium chloride solution from the lithium isooctanoate powder, and then a sodium carbonate solution can be added dropwise to the lithium chloride solution to synthesize lithium carbonate.

[0053] Furthermore, the first raw material crushing step can use a blade mill as a crushing component.

[0054] In addition, the blade mill device may have a pulverizing section at the top for supplying the object to be pulverized, and a pulverizing section including blades for pulverizing at the lower end of the supply section, and a discharge section for discharging the pulverized material at the lower end of the pulverizing section, and the supply section may be used as a first raw material supply component.

[0055] Furthermore, the rotating impeller in the crushing section is blade-shaped, and the crushing section may include a motor component for generating and transmitting rotational power and an external covering component disposed on the outer peripheral surface of the impeller.

[0056] In addition, a liner may be included between the impeller and the external cover to cushion the impact generated during crushing.

[0057] Furthermore, the power generated by the motor component can range from 5 horsepower to 50 horsepower.

[0058] Furthermore, the diameter of the input surface for feeding the object to be crushed or the discharge surface for discharging the object can be from 50 mm to 150 mm, and the diameter of the input surface or the discharge surface can be the same or different.

[0059] Furthermore, the impeller with the blade shape can rotate at 2000 RPM to 6000 RPM.

[0060] In addition, multiple impellers can be formed to improve pulverization efficiency.

[0061] Furthermore, the impeller can be configured with a slope of 5° to 45° relative to the central axis, and when multiple impellers are formed, they can be formed at the same angle or different angles.

[0062] Furthermore, it may include a pulverized material storage step, which stores the pulverized material before mixing the first raw material pulverized in the first raw material pulverizing step, the pulverized material storage step selectively supplying the pulverized material to the mixing step or the first raw material pulverizing step.

[0063] Furthermore, when the pulverized material is supplied to the first raw material pulverizing step, it undergoes multiple pulverization processes, thereby further reducing the particle size and improving the efficiency of the mixing step as well as the purity or yield of the resulting lithium sulfide.

[0064] In addition, to perform the pulverized material storage step, multiple storage components can be provided, each of which can classify and store the pulverized material according to its particle size. To perform the classified storage, a classified storage step can be further included.

[0065] Furthermore, the gap between the external cover component and the impeller can be from 0.5 mm to 20.0 mm; the narrower the gap, the higher the efficiency.

[0066] Furthermore, the carbon molded body can be a porous carbon molded body.

[0067] In addition, the carbon molded body may include any one or more of activated carbon, coke, graphite, graphene, activated carbon, carbon black, and carbon powder.

[0068] Furthermore, the carbon-shaped body may include activated carbon, and the average particle size may be greater than 1µm and less than 1500µm.

[0069] In addition, a preheating step for removing residual moisture may be included as needed after the first raw material crushing step.

[0070] In addition, the preheating step can be from 80°C to 350°C.

[0071] In addition, the sugar may include any one or more of pentose or hexose.

[0072] In addition, the pentose may include xylitol.

[0073] Furthermore, the hexose may include sucrose, glucose, and fructose.

[0074] In addition, sorbitol, which is similar to the hexose mentioned above, can be used.

[0075] In addition, the first solvent may include any one or more of ionic liquids, deionized water, purified water, and distilled water.

[0076] In addition, the second solvent may include any one or more of ionic liquids, ethanol, and acetone.

[0077] Furthermore, the ionic liquid used in the first or second solvent may include [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 = hexylmethyl imidazolium). 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 = trifluoromethanesulfonate) ), [bmim]PF6 (bmim = butyl methyl imidazolium) ), [bmim]BF4 , [omim]PF6 (omim = octyl methyl imidazolium) ), [Oct3PC 18 H 37I, [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 ethylimidazolium)), [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 29The following are any one or more of N(CN)2, N,N-diethyl-N-methyl-N-(2-methoxyethyl)tetraborate ([DEME][BF4]), diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]), dimethylpropylammonium trifluoromethanesulfonate ([dmpa][TfO]), diethylmethylammonium trifluoromethanesulfonylimide ([DEME][TFSI]), and methylpropylpiperidinium trifluoromethanesulfonylimide ([mpp][TFSI]).

[0078] In addition, as mentioned above, the first solvent may include an imidazole ionic liquid, preferably [emim]Cl / AlCl3 (emim = ethylmethylimidazolium).

[0079] In addition, the second solvent may include an amino ionic liquid, more preferably, dimethylpropylammonium.

[0080] If the first and second solvents are not added, the efficiency of lithium sulfide formation may be reduced.

[0081] In addition, the first raw material can be added in the range of 10 to 50 parts by weight, the second raw material can be added in the range of 10 to 50 parts by weight, the first solvent can be added in the range of 50 to 200 parts by weight, and the second solvent can be added in the range of 50 to 200 parts by weight. If the mixing conditions are exceeded, the efficiency of lithium sulfide formation may be reduced.

[0082] Furthermore, the polarity index of the second solvent can be between 4.5 and 6.0.

[0083] In addition, a second solvent extraction step may be included for extracting or removing the second solvent used in the washing step.

[0084] Furthermore, the second solvent may be selected from one or more of methanol, isopropanol, n-propanol, and tetrahydrofuran.

[0085] Furthermore, in the heat treatment step, the heat treatment temperature can be from 500°C to 1500°C.

[0086] Furthermore, the heat treatment temperature is preferably above 700°C.

[0087] Furthermore, the mixing ratio of the first raw material and the second raw material can be from 2:1 to 6:1 by weight.

[0088] Furthermore, in the first raw material crushing step, the first raw material can be crushed to an average particle size of 1µm or more and 10µm.

[0089] Furthermore, the preparation process of the lithium sulfide may include a sulfur feedstock supply step for additionally supplying sulfur feedstock gas.

[0090] Furthermore, the sulfur feedstock supplied through the sulfur feedstock supply step can be stored in a separate storage unit before being supplied.

[0091] In addition, the sulfur feedstock supply step may be included to improve the purity of the prepared lithium sulfide.

[0092] Furthermore, the sulfur feedstock gas supplied in the sulfur feedstock supply step may include any one or more of SO, SO2, and SO3.

[0093] Furthermore, the total pressure of the sulfur feedstock gas supplied in the sulfur feedstock supply step is 1 atmosphere, and the partial pressure can be 1×10⁻⁶. -5 Atmospheric pressure up to 1×10 -2 .

[0094] Furthermore, a pressure regulation step may be included, which uses a separate exhaust pump to regulate the pressure to ensure the pressure distribution.

[0095] Furthermore, the heat treatment step can reach the target heat treatment temperature at a heating rate of 3°C / min to 12°C / min after the start of heating.

[0096] Furthermore, the heat treatment time for the heat treatment step can be 30 seconds or more.

[0097] Furthermore, the heat treatment step can be carried out at atmospheric pressure above 1 atm.

[0098] Furthermore, the preparation of the lithium sulfide can be carried out under an inert gas atmosphere or a vacuum atmosphere.

[0099] Furthermore, an inert gas supply step may be included to provide the inert gas atmosphere.

[0100] Furthermore, a vacuum step may be included to create the vacuum atmosphere.

[0101] In addition, the inert gas may include any one or more of argon, nitrogen, neon, methane, carbon monoxide, methane, ethane, propane, butane, and helium.

[0102] Furthermore, a drying step may be included after the plasticizing step.

[0103] In addition, the drying step can utilize a separate drying unit or employ natural drying.

[0104] Furthermore, the drying step can be carried out at a temperature below 60°C.

[0105] Furthermore, it may include a step of obtaining the prepared lithium sulfide after the plasticizing step.

[0106] Furthermore, in the method for preparing the lithium sulfide, the resources generated through the first evaporation step, the second evaporation step, the second solvent extraction step, etc., can be recovered and reused in the process.

[0107] Furthermore, the resources recovered in the first evaporation step can be the first solvent and can be reused in the mixing step.

[0108] Furthermore, the resources recovered in the second evaporation step can be reused in the washing step.

[0109] Furthermore, the resources recovered in the second solvent recovery step can be reused in the washing step.

[0110] Furthermore, the lithium sulfide obtained can be applied to battery fields such as secondary batteries and all-solid-state batteries.

[0111] Furthermore, the average size of the prepared lithium sulfide can be below 10 µm.

[0112] Furthermore, the purity of the prepared lithium sulfide can be above 99.9%.

[0113] Furthermore, for the aforementioned preparation method, an apparatus for preparing lithium sulfide can be provided, comprising: a first raw material storage unit for storing a first raw material containing lithium; a second storage unit for storing a second raw material containing carbon; a first raw material pulverizing unit for pulverizing the prepared first raw material; a mixing unit for adding the pulverized first and second raw materials to a first solvent to generate a mixture; a first evaporation unit for evaporating the solvent from the mixture; a heat treatment unit for heat treating the mixture; a washing unit for washing the sintered mixture with a second solvent; a second evaporation unit for filtering impurities while evaporating the washed mixture; and a plasticizing unit for plasticizing the mixture after the second evaporation step.

[0114] Furthermore, the preparation method may further include any one or more of the following: a sulfur raw material supply component, a preheating component, an inert gas supply component, a vacuum component, a drying component, a first solvent recovery component, and a second solvent recovery component.

[0115] Those skilled in the art can make various applications and modifications within the scope of this invention based on the above content.

Claims

1. A method for preparing lithium sulfide, comprising: The first raw material preparation step involves preparing a first raw material containing lithium. The second raw material preparation step includes a second raw material containing carbon; The first raw material crushing step involves crushing the prepared first raw material. In the mixing step, the pulverized first and second raw materials are added to the mixture; The first evaporation step involves evaporating the solvent from the mixture; A heat treatment step involves heat treating the mixture. The washing step involves washing the sintered mixture with a second solvent. The second evaporation step involves filtering impurities while evaporating the washed mixture. as well as The plasticizing step involves plasticizing the mixture that has undergone the second evaporation step.

2. The method for preparing lithium sulfide according to claim 1, wherein: The first raw material includes any one or more of lithium oxide, lithium metal, lithium carbonate, lithium hydroxide, lithium sulfate, and lithium isooctanoate.

3. The method for preparing lithium sulfide according to claim 1, wherein: The second raw material includes any one or more of sugar, alcohol and carbon-shaped material.

4. The method for preparing lithium sulfide according to claim 3, wherein: The sugar includes any one or more of pentose or hexose.

5. The method for preparing lithium sulfide according to claim 1, wherein: The first solvent includes any one or more of ionic liquids, deionized water, purified water, and distilled water.

6. The method for preparing lithium sulfide according to claim 1, wherein: The second solvent includes any one or more of ionic liquids, ethanol, and acetone.

7. The method for preparing lithium sulfide according to claim 1, wherein: In the heat treatment step, the heat treatment temperature is 500°C to 1500°C.

8. The method for preparing lithium sulfide according to claim 1, wherein: By weight, the mixing ratio of the first raw material and the second raw material is 2:1 to 6:

1.

9. The method for preparing lithium sulfide according to claim 1, wherein: In the first raw material crushing step, the first raw material is crushed to an average particle size of 1µm to 10µm.

10. The method for preparing lithium sulfide according to claim 1, wherein: The preparation process of the lithium sulfide also includes a sulfur feedstock supply step for additionally supplying sulfur feedstock gas.

11. The method for preparing lithium sulfide according to claim 10, wherein: The sulfur feedstock gas supplied in the sulfur feedstock supply step includes any one or more of SO, SO2 and SO3.

12. The method for preparing lithium sulfide according to claim 10, wherein: The total pressure of the sulfur feedstock gas supplied in the sulfur feedstock supply step is 1 atmosphere, and the partial pressure is 1 × 10⁻⁶. -5 Atmospheric pressure up to 1×10 -2 .

Images