How lithium sulfide is produced

Abstract

To provide a robust and scalable method for producing high purity lithium sulfide using inexpensive precursors. [Solution] A method for producing a water-reactive alkali metal sulfide, the method comprising: (a) reacting a first alkali metal salt and a first alkali metal hydrosulfide, and optionally a first sulfide, in a polar solvent to produce a mixture containing a second sulfide and a second alkali metal salt precipitate; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant containing the second sulfide and the polar solvent; and (c) removing the polar solvent from the supernatant.

Description

[Technical field]

[0001] The present disclosure relates to a method for producing lithium sulfide.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to and claims priority under 35 U.S.C. § 119 from U.S. Provisional Application No. 63 / 264,137, filed November 16, 2021, entitled "METHOD FOR PRODUCING LITHIUM SULFIDE," the entire contents of which are hereby incorporated by reference in their entirety for all purposes. [Background technology]

[0003] In recent years, reliance on secondary batteries for mobile phones, personal computers, automobiles, etc. has rapidly increased. Also, the demand for batteries that can hold more power, last longer, and are more economical is increasing. To meet these growing demands, companies and research alike have focused on solid-state rechargeable batteries, specifically those containing solid sulfide electrolytes.

[0004] One of the main reactants utilized in the synthesis of solid sulfide electrolytes is lithium sulfide (Li 2S). This compound does not occur naturally and must be made synthetically, and traditional synthetic routes require expensive precursors, expensive equipment, and can result in compounds of low purity. For example, Smith (US3642436) teaches reacting an alkali metal with hydrogen sulfide or sulfur vapor, but this method requires expensive high purity lithium metal and the use of large amounts of hydrogen sulfide, a highly toxic gas. Dawidowski (DE102012208982) teaches reacting a lithium metal base with hydrogen sulfide in an organic solvent, but this method also uses expensive precursors in the form of lithium organic compounds. Barker (US8377411) and Mehta (US6555078) both teach processes that use cheaper precursors, but Barker's method requires expensive specialized processing equipment due to the corrosive nature of the process, and Mehta's method requires high temperatures and the use of aqueous solutions, which result in hydrolysis of lithium sulfide and a product of lower purity. To overcome these problems, Li 2 More efficient, lower-cost methods of producing S are needed. Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a robust and scalable method for producing high purity lithium sulfide using inexpensive precursors. [Means for solving the problem]

[0006] The present application includes a method for producing high purity lithium sulfide compounds in which a lithium metal salt is reacted with a hydrosulfide-containing compound in a protic organic solvent in which a substantial solubility difference exists between the newly formed lithium metal hydrosulfide and the alkali metal salt by-products, and the resulting alkali metal salt by-products and protic organic solvent are removed and subjected to a heat treatment to form a high purity lithium sulfide material. [Brief description of the drawings]

[0007] [Figure 1]FIG. 1 shows the x-ray diffraction patterns of lithium sulfide (Li2S) synthesized in Examples 1, 2, 3, 4, and Comparative Example 1. [Diagram 2] FIG. 2 shows the thermogravimetric analysis of the lithium sulfide (Li2S) synthesized in Example 3, Example 4, and Comparative Example 1. [Diagram 3] FIG. 3 shows the x-ray diffraction diagrams of lithium sulfide (LiS) synthesized in Examples 5, 6, and 7. [Figure 4] FIG. 4 shows the x-ray diffraction diagrams of lithium sulfide (LiS) synthesized in Examples 8, 9, and 10. [Diagram 5] FIG. 5 shows the x-ray diffraction diagrams of lithium sulfide (LiS) synthesized in Examples 10, 11, 12, and 13. [Figure 6] FIG. 6 shows the x-ray diffraction diagram of technical grade lithium chloride (LiCl) and lithium sulfide (LiS) synthesized in Example 14. [Figure 7] FIG. 7 shows the x-ray diffraction diagrams of technical grade lithium sulfide (LiS) and lithium sulfide (LiS) synthesized in Example 15. [Figure 8] FIG. 8 shows the x-ray diffraction diagram of the solid electrolyte prepared in Example 16. [Figure 9] FIG. 9 shows the thermogravimetric analysis of lithium sulfide (Li2S) synthesized in Example 5 and Comparative Example 1. [Figure 10] FIG. 10 shows the Fourier transform infrared spectroscopy (FTIR) spectra of the lithium sulfide (Li2S) synthesized in Example 5 and Comparative Example 1. [Figure 11] FIG. 11 shows the x-ray diffraction diagram of lithium sulfide (Li2S) synthesized from only Na2S. [Figure 12] FIG. 12 shows the x-ray diffraction diagram of lithium sulfide (Li2S) synthesized from only Na2S with the addition of an additional 10 wt % LiCl as a reactant. [Figure 13] Figure 13 shows the x-ray diffraction diagram of lithium sulfide (Li2S) synthesized using only Na2S and NaHS·XH2O reactants, with the final product being approximately half Li2S and half LiCl. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] As used herein, the term "high purity" or "high level of purity" can mean at least 85% purity, at least 90% purity, at least 91% purity, at least 92% purity, at least 93% purity, at least 94% purity, at least 95% purity, at least 96% purity, at least 97% purity, at least 98% purity, at least 99% purity, or at least 99.5% purity.

[0009] In one embodiment, a method for producing a water-reactive alkali metal sulfide includes the steps of: (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide in a polar solvent to produce a mixture of a second sulfide, a second alkali metal hydrosulfide, and a second alkali metal salt, where the polar solvent is selected to provide a solubility differential between the second sulfide, which is highly soluble in the polar solvent, the second alkali metal hydrosulfide, which is also highly soluble in the polar solvent, and the second alkali metal salt, which forms a precipitate in the polar solvent; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant comprising the second sulfide, the second alkali metal hydrosulfide, and the polar solvent; and (c) heating the supernatant to remove the polar solvent and convert the second alkali metal hydrosulfide to the second sulfide.

[0010] In another embodiment, a method for producing a water-reactive alkali metal sulfide includes (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide in a polar solvent to produce a mixture of a second sulfide, a second alkali metal hydrosulfide, and the first alkali metal salt, where the polar solvent is selected to provide a solubility differential between the second sulfide, which is highly soluble in the polar solvent, the second alkali metal hydrosulfide, which is also highly soluble in the polar solvent, and the first alkali metal salt, which forms a precipitate in the polar solvent; (b) removing the precipitated first alkali metal salt from the mixture to produce a supernatant comprising the second sulfide, the second alkali metal hydrosulfide, and the polar solvent; and (c) heating the supernatant to remove the polar solvent and convert the second alkali metal hydrosulfide to the second sulfide.

[0011] In another embodiment, the method includes reacting a first alkali metal salt and a first alkali metal hydrosulfide to produce a second alkali metal salt and a first alkali metal sulfide (e.g., LiCl+NaSH→Li 2 S+NaCl). The method can further include isolating the first alkali metal sulfide at a high level of purity.

[0012] In another embodiment, the method includes reacting a first alkali metal salt and a first alkali metal hydrosulfide to produce a second alkali metal salt, a second alkali metal hydrosulfide, and a first alkali metal sulfide (e.g., LiCl+NaSH→Li 2 S+LiSH+NaCl). The method can further include isolating the first alkali metal sulfide at a high level of purity.

[0013] In another embodiment, the method includes reacting a first alkali metal salt with a first alkali metal hydrosulfide to produce a first alkali metal salt, a second alkali metal salt, and a second alkali metal sulfide (e.g., LiCl+NaSH→Li 2S+LiCl+NaCl). The method may further include isolating the first alkali metal sulfide, the first alkali metal salt, and / or the second alkali metal salt, individually or collectively, at a high level of purity.

[0014] In another embodiment, the method includes reacting a first alkali metal salt, a first alkali metal sulfide, and a first alkali metal hydrosulfide to produce a second alkali metal salt and a second alkali metal sulfide (e.g., LiCl+Na 2 S+NaSH→Li 2 S+NaCl). The method can further include isolating the first alkali metal sulfide at a high level of purity.

[0015] In another embodiment, the method includes reacting a first alkali metal salt, a first alkali metal sulfide, and a first alkali metal hydrosulfide to produce a first alkali metal salt, a second alkali metal salt, and a second alkali metal sulfide (e.g., LiCl+Na 2 S+NaSH→Li 2 S+LiCl+NaCl). The method may further include isolating the first alkali metal sulfide, the first alkali metal salt, and / or the second alkali metal salt, individually or collectively, at a high level of purity.

[0016] In another embodiment, a method for producing a water-reactive alkali metal sulfide includes (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide hydrate in a solvent to produce a reaction mixture, (b) heating the reaction mixture, and (c) isolating a purified second sulfide and a purified first alkali metal salt. The solvent may be a hydrocarbon solvent (e.g., a non-polar hydrocarbon sorb), a polar solvent (e.g., a polar organic solvent), or a combination thereof. The purified second sulfide is Li 2The second sulfide and / or the first alkali metal salt may be S and the purified first alkali metal salt may be LiCl. The second sulfide and / or the first alkali metal salt may be optionally recycled as reactants, for example, to further increase the purity of the purified second sulfide and purified first alkali metal salt final products. The reaction mixture may be heated to about 100°C to about 150°C, about 150°C to about 200°C, about 200°C to about 250°C, about 250°C to about 300°C, about 300°C to about 350°C, about 350°C to about 400°C, or about 400°C to about 450°C.

[0017] In another embodiment, a method for producing a water-reactive alkali metal sulfide includes (a) reacting a first alkali metal salt, a first sulfide, a second sulfide, and a first alkali metal hydrosulfide hydrate in a solvent to produce a reaction mixture, (b) heating the reaction mixture, and (c) isolating a third sulfide and a purified first alkali metal salt. The solvent may be a hydrocarbon solvent, a polar solvent (e.g., a polar organic solvent), or a combination thereof. The purified third sulfide is Li 2 The third sulfide and / or the first alkali metal salt may be S and the purified first alkali metal salt may be LiCl. The third sulfide and / or the first alkali metal salt may be optionally recycled as reactants, for example, to further increase the purity of the purified third sulfide and purified first alkali metal salt final products. The reaction mixture may be heated to about 100°C to about 150°C, about 150°C to about 200°C, about 200°C to about 250°C, about 250°C to about 300°C, about 300°C to about 350°C, about 350°C to about 400°C, or about 400°C to about 450°C.

[0018] In yet another embodiment, a method for producing a water-reactive alkali metal sulfide includes (a) reacting a first alkali metal salt, a second alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide hydrate in a solvent to produce a reaction mixture, (b) heating the reaction mixture, and (c) isolating the second sulfide and the purified first alkali metal salt. The solvent may be a hydrocarbon solvent, a polar solvent (e.g., a polar organic solvent), or a combination thereof. The purified second sulfide is Li2 S and the purified first alkali metal salt may be LiCl. In this reaction, the difference in solubility between the first alkali metal salt and the second alkali metal salt results in a substantial increase in the purity of the first alkali metal salt product. The second sulfide and / or the first alkali metal salt may be optionally recycled as reactants, for example, to further increase the purity of the purified second sulfide and purified first alkali metal salt final products. The reaction mixture may be heated to about 100°C to about 150°C, about 150°C to about 200°C, about 200°C to about 250°C, about 250°C to about 300°C, about 300°C to about 350°C, about 350°C to about 400°C, or about 400°C to about 450°C.

[0019] In another embodiment, the claimed method further comprises heating the second sulfide after the polar solvent is removed. In some aspects, the heating comprises sintering.

[0020] In another embodiment, the method further comprises adding a sulfur source to increase the purity of the second sulfide. The sulfur source can be elemental sulfur and H 2 S. The sulfur source can be added at any step in the process, before or during heating of the supernatant.

[0021] In yet another embodiment of the method, the second sulfide is Li, which can be subsequently removed by adding a sulfur source and then a heat treatment step. 3 In yet another embodiment of the method, the second sulfide is LiOCl, which can be subsequently removed by sulfur source addition and a subsequent heat treatment step. 3 It further contains OCl impurities and Li 3 The OCl impurity content is less than 25 wt%, less than 20 wt%, less than 15 wt%, less than 10 wt%, less than 7 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt%. In yet another embodiment of the method, the second sulfide is Li, which may be subsequently removed by sulfur source addition and a subsequent heat treatment step. 3 It further contains OCl impurities and Li 3The OCl contaminant content is less than 25%, less than 20%, less than 15%, less than 10%, less than 7%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1% or less than 0.5% after the heat treatment step.

[0022] In yet another embodiment of the method, the second sulfide further comprises a LiHS contaminant that can be subsequently removed by a heating step. In yet another embodiment of the method, the second sulfide further comprises a LiHS contaminant that can be subsequently removed by a sulfur source addition and subsequent heat treatment step, and the LiHS contaminant content is less than 25 wt%, less than 20 wt%, less than 15 wt%, less than 10 wt%, less than 7 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt%. In yet another embodiment of the method, the second sulfide further comprises a LiHS contaminant that may be subsequently removed by sulfur source addition and a subsequent heat treatment step, and the LiHS contaminant content is less than 25 wt%, less than 20 wt%, less than 15 wt%, less than 10 wt%, less than 7 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, less than 1 wt%, or less than 0.5 wt% after the heat treatment step. 3 The sum of OCl and LiHS may be less than 40 wt%, less than 35 wt%, less than 30 wt%, less than 25 wt%, less than 20 wt%, less than 15 wt%, less than 10 wt%, less than 7 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, less than 1 wt%, or less than 0.5 wt% after the heat treatment step.

[0023] In yet another embodiment, the method further comprises introducing an antisolvent to the supernatant prior to or immediately after precipitation of the second alkali metal salt.

[0024] In yet another embodiment of the method, removing the second alkali metal salt from the supernatant comprises at least one of centrifugation, filtration, gravity settling, and cooling.

[0025] In another embodiment, the method further comprises reducing the amount of polar solvent from the supernatant, where the reducing comprises at least one of evaporating the polar solvent, heating the polar solvent, or reducing the ambient atmospheric pressure surrounding the supernatant.

[0026] In another embodiment, the method further includes manipulating the relative amounts of the first alkali metal salt, the first sulfide compound, and the first alkali metal hydrosulfide compound to increase the purity of the second sulfide.

[0027] In yet another embodiment of the method, the polar solvent is substantially anhydrous. The polar solvent may be at least one alcohol selected from the group consisting of ethanol, 1-propanol, 1-butanol, and mixtures thereof.

[0028] In yet another embodiment of the method, the anti-solvent is selected from one or more hydrocarbon solvents, including, but not limited to, alkanes (e.g., pentane, hexane, heptane, decane, undecane), cyclic alkanes, xylenes, and / or toluene.

[0029] In yet another embodiment of the method, the anti-solvent is selected from heptane and one or more of other non-polar solvents that have substantial miscibility in the polar solvent and increase the solubility difference of one or more of the second sulfide and the second alkali metal hydrosulfide in the polar solvent compared to the second alkali metal salt.

[0030] In yet another embodiment of the method, the first alkali metal salt comprises LiCl and the first alkali metal hydrosulfide is NaHS and / or NaHS·XH 2 O, and the first sulfide is Na 2 Contains S.

[0031] In yet another embodiment of the method, the second alkali metal salt comprises NaCl, the second alkali metal hydrosulfide comprises LiHS, and the second sulfide comprises Li. 2 Contains S.

[0032] In yet another embodiment of the method, the first alkali metal salt and the first sulfide are separately dissolved in aliquots of the polar solvent, and the separate aliquots are then combined to form a mixture prior to adding the first alkali metal hydrogen sulfide.

[0033] In yet another embodiment of the method, the first alkali metal salt, the first sulfide compound, and the first alkali metal hydrosulfide are independently dissolved in a polar solvent prior to reacting them together.

[0034] In yet another embodiment of the method, the first alkali metal salt or the first sulfide is first dissolved in a polar solvent and then the other is added in solid form.

[0035] In yet another embodiment of the method, one of the first alkali metal salt, the first sulfide, and the alkali metal hydrosulfide is dissolved in a polar solvent and the others are added to the solution in solid form.

[0036] In yet another embodiment of the method, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is at least 90:10. In yet another embodiment, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is at least 97:3. In yet another embodiment, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is at least 99:1. In yet another embodiment, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is at least 99.9:0.1.

[0037] In yet another embodiment, the first sulfide compound is 2 S, Na 2 S, (NH4) 2 S, and mixtures thereof.

[0038] In yet another embodiment, the first alkali metal hydrosulfide compound is selected from the group consisting of KHS, NaHS, LiHS, and mixtures thereof.

[0039] In yet another embodiment, the second sulfide is Li 2 Contains S.

[0040] In yet another embodiment, the second sulfide comprises a purity of 95% or greater.

[0041] In yet another embodiment, the second sulfide has a mass loss of less than 13% when heated above 340°C.

[0042] In another embodiment, the present disclosure describes a solid electrolyte including a second sulfide produced by a method for producing a water-reactive alkali metal sulfide, the method including: (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide in a polar solvent to produce a mixture of a second sulfide, a second alkali metal hydrosulfide, and a second alkali metal salt, where the polar solvent is selected to provide a solubility difference between the second sulfide that is highly soluble in the polar solvent, the second alkali metal hydrosulfide that is also highly soluble in the polar solvent, and the second alkali metal salt that forms a precipitate in the polar solvent; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant including the second sulfide, the second alkali metal hydrosulfide, and the polar solvent; (c) heating the supernatant to remove the polar solvent and convert the second alkali metal hydrosulfide to the second sulfide;

[0043] In another embodiment, the second sulfide is Li 2 It's S.

[0044] In another embodiment, the alkali metal hydrosulfide is LiHS.

[0045] In another embodiment, the alkali metal hydrosulfide is NaHS.XH 2 O (e.g., hydrate).

[0046] In another embodiment, the first alkali metal salt comprises LiX, where X is a halogen.

[0047] In another embodiment, the second sulfide is Li 2 S, and the first alkali metal hydrosulfide is LiHS or NaHS·XH 2 O and the first alkali metal salt comprises a lithium halide (e.g., one or more of LiCl, LiBr, LiI). The purified first alkali metal salt can be greater than 94% pure, greater than 95% pure, greater than 96% pure, greater than 97% pure, greater than 98% pure, greater than 98.5% pure, greater than 99% pure, greater than 99.5% pure.

[0048] In another embodiment, the present disclosure describes a solid-state battery containing a second sulfide produced by a method of producing a water-reactive alkali metal sulfide, the method including: (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide in a polar solvent to produce a mixture of a second sulfide, a second alkali metal hydrosulfide, and a second alkali metal salt, where the polar solvent is selected to provide a solubility differential between the second sulfide, which is highly soluble in the polar solvent, the second alkali metal hydrosulfide, which is also highly soluble in the polar solvent, and the second alkali metal salt, which forms a precipitate in the polar solvent; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant including the second sulfide, the second alkali metal hydrosulfide, and the polar solvent; (c) heating the supernatant to remove the polar solvent and convert the second alkali metal hydrosulfide to the second sulfide.

[0049] In another embodiment, the second sulfide is Li 2 It's S.

[0050] In another embodiment, the present disclosure describes a vehicle powered by a battery including a second sulfide produced by a method for producing a water-reactive alkali metal sulfide, the method including: (a) reacting a first alkali metal salt, a first sulfide, and a first alkali metal hydrosulfide in a polar solvent to produce a mixture of a second sulfide, a second alkali metal hydrosulfide, and a second alkali metal salt, where the polar solvent is selected to provide a solubility differential between the second sulfide that is highly soluble in the polar solvent, the second alkali metal hydrosulfide that is also highly soluble in the polar solvent, and the second alkali metal salt that forms a precipitate in the polar solvent; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant including the second sulfide, the second alkali metal hydrosulfide, and the polar solvent; (c) heating the supernatant to remove the polar solvent and convert the second alkali metal hydrosulfide to the second sulfide.

[0051] In another embodiment, the second sulfide is Li 2 S. The second sulfide may be greater than 94% pure, greater than 95% pure, greater than 96% pure, greater than 97% pure, greater than 98% pure, greater than 98.5% pure, greater than 99% pure, greater than 99.5% pure, and / or may be substantially free of lithium oxide (i.e., ≦6.0%, ≦5.0%, ≦4.0%, ≦3.0%, ≦2.0%, ≦1.5%, ≦1.0%, or ≦0.5% lithium oxide).

[0052] In another embodiment, the present disclosure provides a process for the preparation of a liquid electrolyte comprising substantially anhydrous LiCl and Na 2 S and K 2 S with a substantially anhydrous hydrosulfide compound selected from LiHS, NaHS, and KHS in a solvent selected from the group consisting of ethanol, 1-propanol, and 1-butanol to produce a highly soluble Li 2 forming highly soluble LiS alkali metal sulfides and optionally LiHS alkali metal hydrosulfides and low solubility alkali metal salts; 2separating a supernatant containing highly soluble LiHS alkali metal sulfides and, if present, highly soluble LiHS alkali metal hydrosulfides and solvent from a precipitate containing less soluble alkali metal salts; and evaporating the solvent from the supernatant to obtain an isolated Li 2 A method for producing lithium sulfide is described, comprising producing S and LiHS.

[0053] In another embodiment, the present disclosure provides a method for the preparation of lithium halides (e.g., LiCl), Na 2 S and / or K 2 S, as well as sulfide compounds selected from LiHS·XH 2 O, NaHS·XH 2 O and / or KHS XH 2 O in a solvent selected from the group consisting of ethanol, 1-propanol and 1-butanol to produce a highly soluble Li 2 A process for producing alkali metal sulfides and highly soluble LiHS alkali metal hydrosulfides and low solubility alkali metal salts; highly soluble Li 2 separating a supernatant containing highly soluble LiHS alkali metal sulfides and highly soluble LiHS alkali metal hydrosulfides and solvent from a precipitate containing less soluble alkali metal salts; and evaporating the solvent from the supernatant to obtain an isolated Li 2 Lithium sulfide (LiS) and LiCl are produced. 2 A method for producing S) is described below.

[0054] In another embodiment, the method comprises the step of: 2 S and LiHS, LiHS is Li 2 S and H 2 and further comprising heating the mixture to a temperature at which S is converted to S.

[0055] In another embodiment, the method further comprises adding a sulfur source. The sulfur source includes elemental sulfur and H 2 Contains one or more of S.

[0056] In another embodiment, the method further comprises introducing an antisolvent to the highly soluble alkali metal sulfide, the highly soluble alkali metal hydrosulfide and the polar solvent supernatant immediately after precipitation of the low solubility alkali metal salt by-product, the antisolvent being selected from one or more of heptane and other non-polar solvents that are substantially miscible in the polar solvent and increase the solubility differential of the alkali metal sulfide relative to the by-product.

[0057] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method generally includes the steps of reacting a first alkali metal salt and a first alkali metal hydrosulfide and optionally a first sulfide in a polar solvent to produce a mixture containing a second sulfide and a second alkali metal salt precipitate; removing the precipitated second alkali metal salt from the mixture to produce a supernatant containing the second sulfide and a polar solvent; and removing the polar solvent from the supernatant. Also provided herein is a solid electrolyte containing the second sulfide produced by this method.

[0058] In another embodiment, removing the polar solvent from the supernatant comprises evaporating the polar solvent to produce a powder. In some aspects, evaporating comprises drying the powder to remove substantially all of the polar solvent. In some additional aspects, greater than 99% by weight of the polar solvent is removed from the powder.

[0059] In another embodiment, removing the polar solvent from the supernatant comprises spray drying, rotary drying, tray drying, fluidized bed drying, vacuum drying, or a combination thereof.

[0060] In another embodiment, the method further comprises adding a sulfur source to increase the purity of the second sulfide. In some aspects, the sulfur source is elemental sulfur and H 2 In some additional embodiments, the sulfur source is added at any step of the method before or during removal of the polar solvent from the supernatant. In further embodiments, the second sulfide is at least 95% by weight Li 3Free of OCl contaminants.

[0061] In another embodiment, the supernatant further comprises a second alkali metal hydrosulfide. In some aspects, the method comprises heating the second alkali metal hydrosulfide to produce a second sulfide and hydrogen sulfide. In some additional aspects, the second alkali metal hydrosulfide comprises LiHS.

[0062] In another embodiment, the method further comprises introducing an antisolvent to the supernatant prior to or immediately after precipitation of the second alkali metal salt. In some aspects, the antisolvent is selected from the group consisting of a hydrocarbon solvent, a nonpolar solvent, a solvent that is substantially miscible in a polar solvent, a solvent that increases the solubility difference of one or more of the second sulfide and the second alkali metal hydrosulfide in the polar solvent compared to the second alkali metal salt, and combinations thereof.

[0063] In some embodiments, removing the second alkali metal salt from the supernatant comprises at least one of centrifugation, filtration, gravity settling, and cooling.

[0064] In another embodiment, the method further comprises reducing the amount of polar solvent from the supernatant, where the reducing comprises at least one of evaporating the polar solvent, heating the polar solvent, or reducing the ambient atmospheric pressure surrounding the supernatant.

[0065] In another embodiment, the method further comprises increasing the relative amount of the first alkali metal salt, the first sulfide compound, or the first alkali metal hydrosulfide compound to increase the purity of the second sulfide to greater than 95% by weight.

[0066] In another embodiment, the polar solvent is substantially anhydrous. In some additional embodiments, the polar solvent comprises at least one alcohol selected from the group consisting of ethanol, 1-propanol, 1-butanol, and mixtures thereof.

[0067] In another embodiment, the first alkali metal hydrosulfide is substantially anhydrous.

[0068] In another embodiment, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 2: 1. In some additional embodiments, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 3: 1. In still further embodiments, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 4: 1.

[0069] In another embodiment, the first alkali metal salt comprises LiCl, the first alkali metal hydrosulfide comprises NaHS, and the first sulfide comprises Na 2 Contains S.

[0070] In another embodiment, the second alkali metal salt comprises NaCl and the second sulfide comprises Li 2 Contains S.

[0071] In another embodiment, the first alkali metal salt and the first sulfide are dissolved separately in aliquots of a polar solvent, and the separate aliquots are then combined to form a mixture prior to adding the first alkali metal hydrogen sulfide.

[0072] In another embodiment, the first alkali metal salt, the first sulfide compound, and the first alkali metal hydrosulfide are independently dissolved in a polar solvent prior to reacting them together.

[0073] In another embodiment, the first alkali metal salt or the first sulfide is first dissolved in a polar solvent and then the other is added in solid form.

[0074] In another embodiment, one of the first alkali metal salt, the first sulfide, and the first alkali metal hydrosulfide is dissolved in a polar solvent and the others are added to the solution in solid form.

[0075] In another embodiment, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is 90 or more:10. In some additional aspects, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is 97 or more:3. In still further embodiments, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is 99 or more:1. In still further embodiments, the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is 99.9 or more:0.1.

[0076] In another embodiment, the first sulfide compound is K 2 S, Na 2 S, (NH 4 ) 2 S, and mixtures thereof.

[0077] In another embodiment, the first alkali metal hydrosulfide compound is selected from the group consisting of KHS, NaHS, LiHS, and mixtures thereof.

[0078] In another embodiment, the second sulfide is Li 2 In some additional embodiments, the second sulfide has a purity of 95% or greater. In yet other embodiments, the second sulfide has a mass loss of less than 10% when heated above 100° C. In yet other embodiments, the second sulfide has a mass loss of less than 13% when heated above 340° C.

[0079] In another embodiment, the mixture produced further comprises LiNaS. In some additional embodiments, the mixture produced further comprises Li 2 MgS 2 In yet a further embodiment, the resulting mixture further comprises Li 2 CaS 2 Further includes:

[0080] In another embodiment, about 97.5% by weight to about 99.9% by weight of the second sulfide is Na2 S 2 O 3 In yet another embodiment, about 97.5% by weight to about 99.9% by weight of the second sulfide is Na 2 S 2 Contains no contaminants.

[0081] Further provided herein is a method for producing a water-reactive alkali metal sulfide, the method comprising the steps of reacting a first alkali metal salt and a first alkali metal hydrosulfide in a polar solvent to produce a mixture comprising the sulfide and a second alkali metal salt precipitate; removing the precipitated second alkali metal salt from the mixture to produce a supernatant comprising the sulfide and the polar solvent; and removing the polar solvent from the supernatant.

[0082] Further provided herein is a method for producing lithium sulfide, the method comprising the steps of: preparing lithium sulfide by mixing LiCl, a first alkali metal hydrosulfide, and optionally Na 2 S., K. 2 S, and (NH 4 ) 2 A first sulfide comprising one or more of S is reacted in a solvent comprising one or more polar solvents to produce Li 2 In some embodiments, the method includes producing a mixture comprising S and an alkali metal salt. The mixture may include NaCl as a precipitate and dissolved LiCl. In some embodiments, the method includes producing a mixture comprising S and an alkali metal salt. 2 Further provided herein is a method for producing Li2+ from a liquid culture medium comprising the steps of: 2 Provided herein is a solid electrolyte comprising S. Also provided herein is a solid electrolyte comprising LiCl produced by this method.

[0083] In another embodiment, the method further comprises the step of: 2 S, alkali metal salts, or Li 2The method further includes removing the solvent from both S and the alkali metal salt. In some embodiments, removing the solvent includes evaporating the solvent to produce a powder. In some particular embodiments, removing the solvent includes spray drying, rotary drying, tray drying, fluidized bed drying, vacuum drying, or a combination thereof.

[0084] In another embodiment, the polar solvent comprises ethanol, 1-propanol, 1-butanol, or a combination thereof.

[0085] In another embodiment, the first alkali metal hydrosulfide comprises LiHS, NaHS, KHS, or a combination thereof.

[0086] In another embodiment, the first alkali metal hydrosulfide comprises NaHS. In some additional embodiments, the first alkali metal hydrosulfide is substantially anhydrous.

[0087] In another embodiment, the LiCl is substantially anhydrous. In some additional embodiments, the LiCl is from about 100 ppm to about 1500 ppm H 2 In yet a further embodiment, the LiCl contains about 900 ppm to about 1100 ppm H 2 Includes O content.

[0088] In another embodiment, the first sulfide is substantially anhydrous. In some additional embodiments, the first sulfide is from about 100 ppm to about 1500 ppm H 2 In yet a further embodiment, the first sulfide comprises about 900 ppm to about 1100 ppm H 2 Includes O content.

[0089] In another embodiment, the mixture and the supernatant comprise a second alkali metal hydrosulfide.

[0090] In another embodiment, the method further comprises introducing an anti-solvent to the supernatant. In some aspects, the anti-solvent comprises a hydrocarbon solvent, a non-polar solvent, or a combination thereof.

[0091] In another embodiment, the method further comprises adding a sulfur source. In some aspects, the sulfur source is elemental sulfur and H 2 Contains one or more of S.

[0092] In another embodiment, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 2: 1. In some additional embodiments, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 3: 1. In still further embodiments, the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 4: 1.

[0093] In another embodiment, the alkali metal salt produced comprises LiCl.

[0094] In another embodiment, the mixture comprises > 5 wt% LiCl. In some additional embodiments, the mixture comprises > 10 wt% LiCl.

[0095] In another embodiment, the mixture is at least 95% by weight, combined, of Li 2 In some additional embodiments, the mixture comprises at least 98% by weight of Li 2 Contains S and LiCl.

[0096] In another embodiment, Li 2 In some additional embodiments, LiS+LiCl are each produced with a purity of ≧95%. 2 S+LiCl are produced in a combined yield of ≧98%.

[0097] Further provided herein is a method for producing lithium sulfide, the method comprising the steps of: preparing LiX, a first alkali metal hydrosulfide, and optionally Na 2 S., K. 2 S, and (NH 4 ) 2 A first sulfide comprising one or more of S is reacted in a solvent comprising one or more polar solvents to produce Li2 forming a mixture comprising S and an alkali metal salt, wherein X is a halogen.

[0098] In another embodiment, the alkali metal salt produced comprises LiX.

[0099] In another embodiment, the mixture comprises ≧5% by weight LiX. In yet another embodiment, the mixture comprises ≧10% by weight LiX. In yet a further embodiment, the mixture comprises a total of at least 95% by weight LiX. 2 In yet a further embodiment, the mixture comprises at least 98% by weight, combined, of LiS and LiX. 2 Includes S and LiX.

[0100] In another embodiment, Li 2 In yet another embodiment, Li 2 S+LiX are each produced with a purity of ≧98%.

[0101] Further provided herein is a method for producing lithium sulfide. The method generally comprises the steps of: 2 S., K. 2 S, and (NH 4 ) 2 S in a solvent comprising one or more polar solvents to produce Li 2 forming a mixture comprising S and an alkali metal salt.

[0102] Further provided herein is a method for producing a water-reactive alkali metal sulfide, the method comprising the steps of reacting a first alkali metal salt and a first alkali metal hydrosulfide and optionally the first sulfide in a polar solvent to produce a mixture comprising a second sulfide and a second alkali metal salt precipitate, the first sulfide comprising an alkali or alkaline earth metal impurity, the impurity not being lithium; removing the precipitated second alkali metal salt from the mixture to produce a supernatant comprising the second sulfide and the polar solvent; and removing the polar solvent from the supernatant to produce the second sulfide.

[0103] In another embodiment, the first sulfide comprises an alkali or alkaline earth metal impurity selected from the group consisting of sodium, magnesium, potassium, calcium, or combinations thereof.

[0104] In another embodiment, the first sulfide comprises lithium and an alkali or alkaline earth metal impurity selected from the group consisting of sodium, magnesium, potassium, calcium, or combinations thereof.

[0105] In another embodiment, the second sulfide is at least 90% free of alkali metal or alkaline earth metal impurities. In a further embodiment, the second sulfide is at least 95% free of alkali metal or alkaline earth metal impurities. In yet a further embodiment, the second sulfide is at least 98% free of alkali metal or alkaline earth metal impurities. In yet a further embodiment, the second sulfide is at least 99% free of alkali metal or alkaline earth metal impurities. In yet a further embodiment, the second sulfide is at least 99.5% free of alkali metal or alkaline earth metal impurities. In yet a further embodiment, the second sulfide is at least 99.9% free of alkali metal or alkaline earth metal impurities.

[0106] In another embodiment, removing the polar solvent from the supernatant comprises evaporating the polar solvent to produce a powder. In some aspects, evaporating comprises drying the powder to remove substantially all of the polar solvent. In some particular aspects, removing the polar solvent comprises spray drying, rotary drying, tray drying, fluidized bed drying, vacuum drying, or a combination thereof. In some additional aspects, greater than 80% by weight of the polar solvent is removed from the powder. In yet another aspect, greater than 99% by weight of the polar solvent is removed from the powder.

[0107] In another embodiment, the method further comprises adding a sulfur source to increase the purity of the second sulfide. In some aspects, the sulfur source is elemental sulfur and H 2 Contains one or more of S.

[0108] In another embodiment, the second sulfide is at least 95% pure by weight. In yet another embodiment, the second sulfide is at least 98% pure by weight. In a further embodiment, the second sulfide is at least 99% pure by weight. In yet a further embodiment, the second sulfide is at least 99.5% pure by weight.

[0109] In another embodiment, the supernatant further comprises a second alkali metal hydrosulfide. In some aspects, the second alkali metal hydrosulfide produces a second sulfide and hydrogen sulfide. In some additional aspects, the second alkali metal hydrosulfide comprises LiHS.

[0110] In another embodiment, the method further comprises adding an antisolvent to the supernatant. In some aspects, the antisolvent comprises a hydrocarbon solvent, a non-polar solvent, or a combination thereof.

[0111] In another embodiment, the method further comprises removing the second alkali metal salt from the supernatant comprising at least one of centrifugation, filtration, gravity settling, and cooling.

[0112] In another embodiment, the polar solvent is substantially anhydrous. In another embodiment, the polar solvent comprises at least one alcohol selected from the group consisting of ethanol, 1-propanol, 1-butanol, and mixtures thereof.

[0113] In another embodiment, the first alkali metal hydrosulfide is substantially anhydrous.

[0114] In another embodiment, the first alkali metal salt comprises LiCl, the first alkali metal hydrosulfide comprises NaHS, and the first sulfide comprises Na 2 Contains S.

[0115] In another embodiment, the second alkali metal salt comprises NaCl and the second sulfide comprises Li 2 Contains S.

[0116] In another embodiment, the optional first sulfide is K 2 S, Na 2 S, (NH 4 ) 2 In another embodiment, the optional first sulfide is selected from the group consisting of Li, S, and mixtures thereof. 2 Contains S.

[0117] In another embodiment, the first alkali metal hydrosulfide compound is selected from the group consisting of KHS, NaHS, LiHS, and mixtures thereof.

[0118] In another embodiment, the second sulfide is Li 2 Contains S.

[0119] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method includes reacting a first alkali metal salt and a first alkali metal hydrosulfide and a first sulfide in a polar solvent to produce a mixture containing a second sulfide and a second alkali metal salt precipitate, where the first sulfide contains oxygen impurities, halide impurities, or a combination thereof; removing the precipitated second alkali metal salt from the mixture to produce a supernatant containing the second sulfide and the polar solvent; and removing the polar solvent from the supernatant to produce the second sulfide.

[0120] In another embodiment, the first sulfide comprises a halide impurity selected from the group consisting of chloride, bromide, iodide, fluoride, or combinations thereof.

[0121] In another embodiment, the first sulfide comprises an oxygen impurity selected from the group consisting of carbonates, sulfates, hydroxides, oxides, or combinations thereof.

[0122] In another embodiment, the second sulfide is at least 90% free of halide impurities. In yet another embodiment, the second sulfide is at least 95% free of halide impurities. In yet another embodiment, the second sulfide is at least 98% free of halide impurities. In yet another embodiment, the second sulfide is at least 99% free of halide impurities. In yet another embodiment, the second sulfide is at least 99.5% free of halide impurities. In yet another embodiment, the second sulfide is at least 99.9% free of halide impurities.

[0123] In another embodiment, the second sulfide is at least 90% free of oxide impurities. In yet another embodiment, the second sulfide is at least 95% free of oxide impurities. In yet another embodiment, the second sulfide is at least 98% free of oxide impurities. In yet another embodiment, the second sulfide is at least 99% free of oxide impurities. In yet another embodiment, the second sulfide is at least 99.5% free of oxide impurities. In yet another embodiment, the second sulfide is at least 99.9% free of oxide impurities.

[0124] In another embodiment, the second sulfide is at least 90% free of impurities. In yet another embodiment, the second sulfide is at least 95% free of impurities. In yet another embodiment, the second sulfide is at least 98% free of impurities. In yet another embodiment, the second sulfide is at least 99% free of impurities. In yet another embodiment, the second sulfide is at least 99.5% free of impurities. In yet another embodiment, the second sulfide is at least 99.9% free of impurities.

[0125] Further provided herein is a method for producing a water-reactive alkali metal sulfide, the method comprising reacting a first alkali metal salt and a first sulfide in a polar solvent to produce a mixture comprising a second sulfide and a second alkali metal salt precipitate, removing the precipitated second alkali metal salt from the mixture to produce a supernatant comprising the second sulfide and the polar solvent, and removing the polar solvent from the supernatant to produce the second sulfide.

[0126] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method generally includes reacting a first alkali metal salt and a first alkali metal hydrosulfide in a polar solvent to produce a mixture containing a sulfide and a second alkali metal salt precipitate, where the first alkali metal salt contains an alkali or alkaline earth metal impurity, and the impurity is not lithium; removing the precipitated second alkali metal salt from the mixture to produce a supernatant containing the sulfide and the polar solvent; and removing the polar solvent from the supernatant to produce the sulfide.

[0127] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method generally includes reacting a first alkali metal salt and a first alkali metal hydrosulfide and optionally the first sulfide in a polar solvent to produce a mixture including a second sulfide and a second alkali metal salt, where the first alkali metal salt includes an alkali or alkaline earth metal impurity, and the impurity is not lithium, and removing the polar solvent to isolate the second sulfide and / or the second alkali metal salt.

[0128] In another embodiment, the first alkali metal salt comprises lithium and an alkali or alkaline earth metal impurity selected from the group consisting of sodium, magnesium, potassium, calcium, or combinations thereof.

[0129] In another embodiment, the second sulfide is at least 90% free of alkali metal or alkaline earth metal impurities. In yet another embodiment, the second sulfide is at least 95% free of alkali metal or alkaline earth metal impurities. In yet another embodiment, the second sulfide is at least 98% free of alkali metal or alkaline earth metal impurities. In yet another embodiment, the second sulfide is at least 99% free of alkali metal or alkaline earth metal impurities. In yet another embodiment, the second sulfide is at least 99.5% free of alkali metal or alkaline earth metal impurities.

[0130] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method generally includes reacting a first alkali metal salt and a first alkali metal hydrosulfide and optionally a first sulfide in a polar solvent to produce a mixture containing a second sulfide and a second alkali metal salt precipitate, where the first alkali metal salt contains an alkali or alkaline earth metal impurity, and the impurity is not lithium; removing the precipitated second alkali metal salt and optionally one or more alkaline earth metal sulfides from the mixture to produce a supernatant containing the second sulfide and the polar solvent; and removing the polar solvent from the supernatant to produce the second sulfide.

[0131] Further provided herein is a method for producing a water-reactive alkali metal sulfide. The method generally includes reacting a first alkali metal salt and a first alkali metal hydrosulfide and optionally a first sulfide in a polar solvent to produce a mixture including a second sulfide, a second alkali metal salt, a third sulfide and a first alkali metal salt, where the first alkali metal salt includes an alkali or alkaline earth metal impurity, and the impurity is not lithium; removing the precipitated second alkali metal salt and the precipitated third sulfide; and removing the polar solvent to isolate the second sulfide and / or the first alkali metal salt.

[0132] BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure can be understood by reference to the following detailed description in conjunction with the drawings, which are briefly described below.

[0133] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS In the following description, specific details are provided to provide a thorough understanding of the various aspects of the present disclosure. Moreover, some known methods, processes, devices, and systems in the various aspects described herein are not disclosed in detail to avoid obscuring the technology.

[0134] The present disclosure provides a low-cost synthesis of sulfides by dissolving an alkali metal hydrosulfide and an alkali metal salt in an aliphatic alcohol and / or similar solvent where a "double ion exchange" occurs. The end result is the synthesis of a metal hydrosulfide and one or more alkali metal by-products, where the one or more by-products can be filtered out by appropriate selection of a solvent or addition of a poor solvent such as, but not limited to, a non-polar hydrocarbon, and then filtering out the undesired product or products. The solvent or solvents are then removed, optionally leaving an alkali metal hydrosulfide, which upon heating decomposes into hydrogen sulfide and the desired sulfide as a high purity product. Common reactions include: 1.Metathesis reaction in ethanol NaHS (EtOH) +LiCl (EtOH) →LiHS (EtOH) +NaCl(s) 2. Filter to remove by-products LiHS (EtOH) +NaCl(s) →LiHS (EtOH) 3. Remove the ethanol and heat to form the desired alkali metal sulfide. 2 Remove S 2LiHS (EtOH) →Li 2 S (s) +H 2 S (g) →Li 2 S (s)

[0135] In another embodiment, the metathesis reaction can be summarized by the following equation: 1.Metathesis reaction in ethanol Na 2 S+2LiCl→Li 2 S+2NaCl

[0136] The above reaction is 2 This can be carried out by dissolving the starting materials in ethanol, which can provide a double ion exchange (metathesis) reaction to form S and NaCl.2 S has a very low solubility in ethanol compared to NaCl, so that NaCl can be removed by filtration and Li dissolved in ethanol can be removed by filtration. 2 S remains, which can be removed via a drying process. 2 CO 3 , Li 2 O and Li 3 OCl (e.g., impurity composites), individually or collectively, can be produced in amounts of 10 wt.% or less, 7 wt.% or less, 5 wt.% or less, 4 wt.% or less, 3 wt.% or less, 2 wt.% or less, 1 wt.% or less, or 0.5 wt.% or less, and can be removed by heating the composite material while exposing it to a sulfur source.

[0137] In yet another embodiment, NaHS can optionally be used to generate LiHS, as summarized by the following formula: Na 2 S+2NaHS+4LiCl→Li 2 S+2LiHS+4NaCl→2Li 2 S+H 2 S+4NaCl

[0138] As noted above, LiHS can be heated and / or reacted at temperatures at or above 150° C. (e.g., from about 150° C. to about 300° C.) to produce Li 2 S and H 2 By introducing a sulfur source at high temperature, Li 2 CO 3 , Li 2 O and / or Li 3 Composites containing OCl can be removed or eliminated individually or collectively in amounts of 10 wt % or less, 7 wt % or less, 5 wt % or less, 4 wt % or less, 3 wt % or less, 2 wt % or less, 1 wt % or less, or 0.5 wt % or less.

[0139] In a further embodiment, NaHS may optionally be reacted in a hydrated form and / or with water, as summarized by the following equation: Na 2S+2NaHS·XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→3Li 2 S+H 2 S+4NaCl and / or Na 2 S+2NaHS+XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→3Li 2 S+H 2 S+4NaCl

[0140] As noted above, NaHS may be used in "wet" form, e.g., containing X moles of hydrate or X moles of H 2 In the above formula, NaHS·XH 2 The NaHSO (or similar hydrate) may contain about 20% to about 75% water by weight, about 15% to about 70% water by weight, about 10% to about 65% water by weight, about 5% to about 65% water by weight, about 0% to about 55% water by weight, about 20% to about 50% water by weight, about 20% to about 45% water by weight, about 20% to about 40% water by weight, about 20% to about 35% water by weight, about 20% to about 30% water by weight, about 20% to about 25% water by weight, or about 25% to about 30% water by weight. However, experimentally, the "wet form" of NaHS may be expressed as Na 2 Combining S with LiCl (i.e., Na 2 S+2NaHS·XH 2 O+4LiCl), lithium sulfide, and lithium chloride are generated, and lithium oxide is not substantially generated (i.e., 2Li 2 It has been discovered that the reaction can occur: S + 2LiCl + no Li oxide. Thus, the experimental results suggest that the following reaction can occur: Na 2 S+2NaHS·XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→2Li 2 S+2LiCl+Li oxide free and / or Na 2S+2NaHS+XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→2Li 2 S+2LiCl+Li oxide free and / or Na 2 S+2NaHS·XH 2 O+4LiCl→2Li 2 S+2LiCl+Li oxide free

[0141] In some embodiments, among the starting materials, NaHS·XH 2 Only O is in the "wet" or hydrated form. Thus, in one embodiment, Na 2 S and LiCl are in dry and / or anhydrous form, and NaHS XH 2 O is in the "wet" or hydrated form prior to the reaction, whereas the final product Li 2 The S and LiCl are ultra-94% pure, ultra-95% pure, ultra-96% pure, ultra-97% pure, ultra-98% pure, ultra-98.5% pure, ultra-99% pure, ultra-99.5% pure, and substantially free of lithium oxide (i.e., ≦6.0%, ≦5.0%, ≦4.0%, ≦3.0%, ≦2.0%, ≦1.5%, ≦1.0%, or ≦0.5% lithium oxide). Other potential benefits to the reactions described herein are that one or more of the following may occur: (1) the final product LiCl may be recycled back into the starting material to increase the purity of LiCl; (2) "dirty" or industrial grade LiCl (e.g., LiCl having a purity of 97% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, or 50% or less) may be "cleaned" or purified by incorporating the low purity "dirty" LiCl into the starting reaction and producing LiCl having a purity that is at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% higher than the LiCl starting material; and (3) the final product LiCl may be "cleaned" or purified by incorporating the low purity "dirty" LiCl into the starting reaction and producing LiCl having a purity that is at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% higher than the LiCl starting material.2 S is recycled to the starting material, Li 2 (4) The purity of S can be further increased, and the low purity "dirty" Li 2 S (e.g., Li with a purity of about 97% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, or 50% or less) 2 S) into the starting reaction, and Li 2 Li of at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% greater purity than the S starting material. 2 and / or (5) converting impurities to insoluble sulfides. Generally, the impurities may be insoluble oxides, thus preventing the formation of other oxide impurities. In one aspect, for 95% purity, this low purity "dirty" LiCl may be "cleaned" or purified by incorporating it into the starting reaction to obtain LiCl of ≧99% purity. Yet another surprising aspect of the reactions described herein is that they can be used to make novel and highly pure LiNaS materials (i.e., individually and / or collectively at least 55% pure, at least 60% pure, at least 65% pure, at least 70% pure, at least 75% pure, at least 80% pure, at least 85% pure, at least 90% pure, at least 91% pure, at least 92% pure, at least 93% pure, at least 94% pure, at least 95% pure, at least 96% pure, at least 97% pure, at least 98% pure, at least 99% pure, at least 99.5%). The reaction can be summarized as follows: Na 2 S+2NaHS·XH 2 O+4LiCl→4LiNaS

[0142] The "dirty" or technical grade LiCl referred to herein may contain impurities including salts such as sodium salts, potassium salts, magnesium salts, silicon salts, iron salts, nickel salts, copper salts, etc. In some embodiments, the salts include sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl), etc. 2 ), magnesium chloride (MgCl 2 ), silicon chloride (SiCl 2 ), iron chloride (FeCl 2 ), Nickel chloride (NiCl 2 ), and copper chloride (CuCl 2 All of these salts (except sodium chloride and potassium chloride) are highly soluble in alcohol and therefore cannot be removed by simple filtration with an alcohol solvent. 2 By adding S or NaHS and dissolving in ethanol, the undesired chloride salts can be converted (transformed) into metal sulfides, which are insoluble in alcohol.

[0143] "Dirty" or industrial grade Li 2 S is lithium hydroxide (LiOH), lithium sulfate (Li 2 SO 4 ), carbon, lithium carbonate (Li 2 CO 3 ), and lithium oxide (Li 2 O).

[0144] Wet form of sodium 2 When S is used, water reacts with the lithium in the LiCl to form different Li-O-containing species (Li 2 O, Li 2 CO 3 However, surprisingly, when NaHS contains water in the form of a hydrate, and contains the above non-limiting weight percentages of water, the hydrate does not react with lithium or any undesirable contaminants or impurities (Li 2 O, Li 2 CO 3 , Li 3The resulting material can be heated and / or dried at about 100°C to about 150°C, about 150°C to about 200°C, about 200°C to about 250°C, about 250°C to about 300°C, about 300°C to about 350°C, about 350°C to about 400°C, or about 400°C to about 450°C. Na 2 S+2NaHS·XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→3Li 2 S+H 2 S+4NaCl+LiCl and / or Na 2 S+2NaHS+XH 2 O+4LiCl→Li 2 S+2LiHS+4NaCl→3Li 2 S+H 2 S+4NaCl+LiCl

[0145] The reaction also proceeds without substantial Li-based impurities (i.e., the expected Li 3 OCl impurity is excluded), and the final product is Li 2 It can also be used to produce S and LiCl. The Li produced by this reaction 2 The S and LiCl may be substantially free of impurities (i.e., individually and / or collectively at least 75% pure, at least 80% pure, at least 85% pure, at least 90% pure, at least 91% pure, at least 92% pure, at least 93% pure, at least 94% pure, at least 95% pure, at least 96% pure, at least 97% pure, at least 98% pure, at least 99% pure, at least 99.5% pure). In one embodiment, the LiCl produced by this reaction is 2 S and LiCl are 2 O, Li 2 CO 3 , Li 3 OCl, LiOH, Li 2 SO 4 , Li 2 CO 3and combinations thereof. 2 S and LiCl are at least 75% free of impurities, at least 80% free of impurities, at least 85% free of impurities, at least 90% free of impurities, at least 95% free of impurities, at least 96% free of impurities, at least 97% free of impurities, at least 98% free of impurities, at least 99% free of impurities, or at least 99.5% free of impurities, and these impurities are not included in the Li 2 O, Li 2 CO 3 , Li 3 OCl, LiOH, Li 2 SO 4 , Li 2 CO 3 and combinations thereof. This high degree of purity is unexpected and surprising.

[0146] The reaction also proceeds without substantial impurities (i.e., the expected Li 3 The final product is Li 2 The reaction can be used to produce LiCl and LiS. 2 The S and LiCl may be substantially free of impurities (i.e., individually and / or collectively at least 75% pure, at least 80% pure, at least 85% pure, at least 90% pure, at least 91% pure, at least 92% pure, at least 93% pure, at least 94% pure, at least 95% pure, at least 96% pure, at least 97% pure, at least 98% pure, at least 99% pure, at least 99.5% pure). In one embodiment, the LiCl produced by this reaction is 2 S and LiCl, NaCl, KCl, CaCl, MgCl, SiCl 2 , FeCl 2 , NiCl 2 , CuCl 2The LiS produced by this reaction may be substantially free of impurities selected from the group consisting of CaS, MgS, FeS, NiS, and combinations thereof. 2 S and LiCl are at least 75% free of impurities, at least 80% free of impurities, at least 85% free of impurities, at least 90% free of impurities, at least 95% free of impurities, at least 96% free of impurities, at least 97% free of impurities, at least 98% free of impurities, at least 99% free of impurities, at least 99.5% free of impurities, and impurities are NaCl, KCl, CaCl, MgCl, SiCl 2 , FeCl 2 , NiCl 2 , CuCl 2 , CaS, MgS, FeS, NiS, and combinations thereof. This high degree of purity is unexpected and surprising.

[0147] In one embodiment, standard Na 2 In the synthesis of S only, the final product was Li with a purity of about 94.0%. 2 S, the major impurity being NaCl and the minor impurity being Li 3 OCl and Li 3 The decomposition product of OCl is Li 2 The blue peak in the X-ray diffraction spectrum shown in FIG. 11 is Li with a purity of 94.0%. 2 S and ≦6.0% impurities (e.g., Li 3 OCl).

[0148] In another embodiment, standard NaCl was added with an additional 10 wt. % LiCl as a reactant. 2 In the synthesis of S only, the final product was Li with a purity of about 80.8%. 2 S can be produced, and the main impurity is Li 3 The red peak in the X-ray diffraction spectrum shown in FIG. 12 is LiCl with a purity of 80.8%. 2In one embodiment, NaS is used with an additional 10% LiCl as a reactant. 2 In the synthesis of S only (e.g., no water or hydrates), the Li 3 The amount of OCl increases significantly.

[0149] In yet another embodiment, NaHS·XH 2 The final product is about half Li 2 The black peak in the X-ray diffraction spectrum shown in FIG. 13 represents 51.5% LiS and about half LiCl, each with a purity of over 95%. 2 The final product is 51.5% Li 2 S, 47.5% LiCl, and 1% unidentified. However, each of these reaction products is produced with a purity of ≧95%.

[0150] However, one aspect of the unexpected result was that NaHS·XH 2 Using the LiO reaction 3 About 45% to about 55% LiCl and about 45% to about 55% Li without producing OCl (i.e., less than 1.0%, less than 0.5%, less than 0.3%, less than 0.1%, less than 0.01 wt%) 2 It may be possible to simultaneously produce S (i.e., a complex reaction product). In other words, Na 2 S+2NaHS·XH 2

[0023] In one embodiment, the method comprises the steps of: combining O+4LiCl to produce a total yield of at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or at least 99.9% or more of LiO. 2S and LiCl can be produced by adjusting the reaction conditions to produce about 0% to about 5%, about 5% to about 15%, about 15% to about 25%, about 25% to about 35%, about 35% to about 45%, about 45% to about 55%, about 55% to about 65%, about 65% to about 75%, about 75% to about 85%, about 85% to about 95%, about 95% to about 99% LiCl, and about 0% to about 5%, about 5% to about 15%, about 15% to about 25%, about 25% to about 35%, about 35% to about 45%, about 45% to about 55%, about 55% to about 65%, about 65% to about 75%, about 75% to about 85%, about 85% to about 95%, about 95% to about 99% Li 2 Similarly, you can get Na 2 S+2NaHS+XH 2 O + 4LiCl combined, Li 2 S and LiCl can be produced in a combined yield of at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.7%, or at least 99.9%.

[0151] In the FT-IR spectrum shown in Figure 10, the red line represents the standard "Na 2 Only "S" is synthetic and the material can be dried up to 100 °C. The other lines in the spectrum are from 33% NaHS·XH 2 O and dried at 100 °C (green), 200 °C (blue), and 250 °C (purple). For the three non-red spectra, there can be a significant reduction in the peaks associated with the residual solvent (ethanol) (2750-3000) and the peaks associated with the ethoxide (850-1500). This is because NaHS is converted to Na 2 S and H 2 H by decomposition into S 2 This may be evidence of the production of S. This may also be evidence of the formation of LiHS, which in turn is 2 S or H 2 It is decomposed into S.

[0152] In the thermogravimetric analysis shown in FIG. 9, the line labeled Example 5 is a 33% NaHS·XH2 The reaction is carried out at temperatures between 100°C and about 200°C, and the product is dried so that ≥97%, ≥98%, ≥99%, or ≥99.5% of the total solvent is LiO. 2 In such an embodiment, the reaction described herein is used to prepare dry nanoside Li at temperatures of 100° C. or less, 150° C. or less, 200° C. or less, 250° C. or less, 300° C. or less, 350° C. or less, 400° C. or less, or 450° C. or less. 2 In yet another embodiment, Li 2 The average crystal size of the S reaction product can be from about 0.50 to 1.50 microns in diameter, from about 0.75 to 1.25 microns in diameter, from about 1 to about 3 microns in diameter, from about 1 to about 7 microns in diameter, from about 1 to about 10 microns in diameter, from about 0.5 to about 3 microns in diameter, from about 0.5 to about 5 microns in diameter, from about 0.5 to about 7 microns in diameter, or from about 0.5 to about 10 microns in diameter, or from about 0.5 to about 25 microns in diameter.

[0153] In another embodiment, NaHS·XH 2 Using the O reaction, Li 2 Composites of S with lithium halides (LiF, LiCl, LiBr, LiI) can be produced. This can be achieved by initiating a reaction with an excess of one or more of the lithium halides.

[0154] In another embodiment, the present disclosure provides a low-cost synthesis of sulfides (and / or purified alkali metal salts) by dissolving a first alkali metal hydrosulfide, a first sulfide, and a first alkali metal salt in an aliphatic alcohol and / or similar solvent where a "double ion exchange" occurs. The end result is the synthesis of a second alkali metal hydrosulfide, a second sulfide, and one or more of a purified first alkali metal salt or second alkali metal salt by-product, where the one or more by-products can be precipitated and removed by appropriate selection of a solvent or addition of a poor solvent such as, but not limited to, a non-polar hydrocarbon, and then filtering the undesired one or more products. The one or more solvents can then be removed, leaving the second alkali metal hydrosulfide and the second sulfide, and upon heating, the second alkali metal hydrosulfide decomposes into hydrogen sulfide and the desired second sulfide. The released hydrogen sulfide can then convert any metal oxide species into the desired second sulfide. The end product is a high purity second sulfide and / or a high purity alkali metal salt. One common response is: 1.Metathesis reaction in ethanol NaHS (EtOH) +Na 2 S (EtOH) +LiCl (EtOH) →LiHS (EtOH) +Li 2 S (EtOH) +NaCl (s) 2. Filter to remove by-products LiHS (EtOH) +Li 2 S (EtOH) +NaCl (s) →LiHS (EtOH) +Li 2 s (EtOH) 3. Remove the ethanol, heat and 2 Remove S 2LiHS (EtOH) +Li 2 S (EtOH) →2Li 2 S (s) +H 2 S(g) →2Li 2 S (s)

[0155] The present disclosure illustrates a process for producing lithium sulfide by a double ion exchange reaction occurring in a polar organic solvent, where the reactants are one or more of a lithium metal salt, one or more alkali metal hydrosulfides, and one or more alkali metal sulfide compounds, thereby producing lithium sulfide, lithium hydrosulfide, and one or more alkali metal salts. The particular lithium metal salt, alkali metal hydrosulfide, alkali metal sulfide, and polar organic solvent should be selected such that the lithium metal salt, alkali metal hydrosulfide, and alkali metal sulfide have high solubility in the polar solvent, and the newly formed alkali metal salt produced from the ion exchange reaction has low solubility in the polar organic solvent. The newly formed alkali metal salt has low solubility in the polar organic solvent, precipitates, and is removed from the solution containing lithium sulfide and lithium hydrosulfide. The polar organic solvent is removed to leave a complex of lithium metal hydrosulfide and lithium sulfide. This composite is then heated to produce alkali metal sulfide through the decomposition of lithium hydrosulfide to lithium sulfide and release hydrogen sulfide gas, which serves to reduce any oxide species, thereby resulting in a high purity lithium sulfide product.

[0156] In the method of the present disclosure, the first alkali metal salt and the second alkali metal salt may be, but are not limited to, one or more of LiF, LiCl, LiBr, and LiI. The first alkali hydrosulfide may be, but are not limited to, one or more of LiHS, NaHS, or KHS. The first alkali hydrosulfide, such as LiHS, NaHS, or KHS, may be substantially anhydrous or dried. In an alternative embodiment, the first alkali hydrosulfide, such as LiHS, NaHS, or KHS, may be in a hydrate form. The first alkali hydrosulfide, such as LiHS, NaHS, or KHS, may include a water content of about 0% to about 30%, about 5% to about 25%, about 10% to about 20%, about 15% to about 30%, about 20% to about 30%, about 20% to about 25%, or about 25% to about 30%. The first alkali metal hydrosulfide, such as LiHS, NaHS, and / or KHS, in hydrate form, may have a water content of about 20% to about 75%, about 25% to about 80%, or about 30% to about 85%. The first alkali metal salt and the first alkali metal hydrosulfide compound may be in the form of one or more of, but not limited to, a powder, a pellet, a flake, or a brick.

[0157] In some embodiments, the present disclosure provides Li 2A method for producing S materials is described. In this method, lithium sulfide is produced by a double ion exchange reaction occurring in a polar organic solvent, where the reactants are one or more of lithium metal salts, one or more of alkali metal hydrosulfide compounds, and one or more of alkali metal sulfides. From this stage of the method, lithium sulfide, lithium hydrosulfide, and alkali metal salt by-products are produced. The combination of lithium metal salt, alkali metal hydrosulfide, alkali metal sulfide, and polar organic solvent should be selected such that the lithium metal salt, alkali metal hydrosulfide, and alkali metal sulfide have high solubility in the polar solvent, and the newly formed alkali metal salt produced from the ion exchange reaction has low solubility in the polar organic solvent. The newly formed alkali metal salt has low solubility in the polar organic solvent, precipitates, and is removed from the mixture containing lithium hydrosulfide and lithium sulfide. The polar organic solvent is removed from the mixture of lithium hydrosulfide and lithium sulfide. A mixture of lithium hydrosulfide and lithium sulfide is heated to a point where the lithium hydrosulfide decomposes into lithium sulfide and hydrogen sulfide. The newly produced hydrogen sulfide assists in the reduction of any latent oxide species formed, leaving the lithium sulfide highly pure.

[0158] According to one embodiment of the present disclosure, the sulfide precursor compound is Li 2 S, Na 2 S., K. 2 S, and (NH 4 ) 2The lithium-containing salt may include, but is not limited to, one or more of LiF, LiCl, LiBr, and LiI. The first alkali metal hydrosulfide may be, but is not limited to, one or more of LiHS, NaHS, or KHS, or hydrates thereof. The lithium-containing salt and hydrosulfide may be in the form of, but is not limited to, one or more of powder, pellet, flake, or brick. In some embodiments, hydrosulfides of any monovalent cation or sulfides of any monovalent cation that are soluble in a polar organic solvent may be used as long as the corresponding alkali metal salt by-product has a lower solubility than the solubility of lithium sulfide and lithium hydrosulfide. The low solubility alkali metal salt may be referred to as a low solubility by-product and may be one or more of alkali metal halides including sodium or potassium, such as NaCl, NaBr, NaI, KCl, KBr, KI, etc. In another embodiment, the low solubility alkali metal salt may include rubidium and cesium, and may be one or more of RbCl, RbBr, RbI, CsCl, CsBr, and CsI.

[0159] To facilitate the double ion exchange reaction between the starting materials, one or more alkali metal salts, one or more sulfide compounds, and one or more hydrosulfide compounds can be added individually or together to one or more polar organic solvents. In some embodiments, one or more alkali metal salts, one or more sulfide compounds, and one or more hydrosulfide compounds can be combined before being added to one or more polar organic solvents. The combination of these materials can result from blending, mixing, grinding, or milling of the starting materials. In another embodiment, one or more alkali metal salts, one or more sulfide compounds, and one or more hydrosulfide compounds may be independently dissolved in a solution before other starting materials are combined to form a combined solution. Polar organic solvents include, but are not limited to, one or more alcohols or diols. In some embodiments, the alcohol may be one or more of primary, secondary, or tertiary alcohols. In another embodiment, the alcohol may be one or more of ethanol, 1-propanol, and 1-butanol. In further embodiments, the alcohol may be one or more of isopropanol, isobutanol, and isopentanol. In some embodiments, the solvent may include, but is not limited to, diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. The solvent is not particularly limited as long as the solubility of the alkali metal hydrosulfide and alkali metal sulfide remains higher than the solubility of the alkali metal salt by-product.

[0160] In some embodiments, if the alkali metal hydrosulfide and alkali metal salt by-products produced from the reaction have substantially similar solubilities in polar organic solvents, purification of the desired lithium sulfide product may be complicated. In another embodiment, if the temperature used during dissolution is too high, undesirable side reactions between the precursors and the solvent may occur, potentially reducing the purity or yield of the final lithium sulfide product. In a further embodiment, if the temperature used during dissolution is too low, the solubility of the starting materials may be too low to allow the reaction to proceed.

[0161] When operated at room temperature, 25° C., one or more by-products produced from this reaction can spontaneously precipitate out of solution to form a mixture containing one or more highly soluble lithium sulfide and lithium hydrosulfide in the supernatant, and a precipitate of less soluble alkali metal salt by-products. The rate of precipitation can be altered by introducing cooling. In addition, cooling can also result in further precipitation of one or more less soluble alkali metal by-products.

[0162] To further manipulate the purity level, the ratios and amounts of the various starting materials and polar organic solvents are not particularly limited and may be altered as long as the alterations allow the synthesis of lithium sulfide to proceed. In some embodiments, the volume or weight ratio of the solvent to the amount of individual precursors may be adjusted to prevent side reactions. In some embodiments, if it is desired to synthesize a composite lithium sulfide and alkali metal salt, additional lithium salt or other alkali metal salt may be added. In another embodiment, a lesser amount of one or more polar solvents may be used than is required for complete dissolution of one or more of the lithium salt, alkali metal sulfide, or alkali metal hydrosulfide. In such an embodiment, grinding or milling a mixture of at least one or more lithium salts and an alkali metal hydrosulfide in one or more polar organic solvents may produce the desired lithium sulfide while using less solvent overall. In further embodiments, the described compounds may be mixed with a non-polar solvent, including, but not limited to, heptane, octane, benzene, toluene, and xylene. In another embodiment, additional materials such as co-solvents or flocculants may also be added to aid in the removal of precipitated alkali metal salt by-products.

[0163] Stirring or other mixing can be used to homogenize the solution, and mixing times are not particularly limited, so long as they allow for adequate homogenization and reaction of the precursors to produce lithium hydrosulfide and / or lithium sulfide, and one or more alkali metal salt by-products. The mixing temperature is not particularly limited, so long as they allow for adequate mixing and are not so high as to promote the formation of undesirable materials or so low as to suppress the solubility of one or more alkali metal sulfides or hydrosulfides to the point of reaction termination. In some embodiments, mixing can be carried out at a temperature ranging from -50°C to 120°C, for example, using a magnetic stirrer or shaft mixer. In another embodiment, the temperature range can be from -40°C to 100°C. In yet another embodiment, the temperature range can be from -30°C to 80°C. In yet another embodiment, the temperature range can be from -20°C to 60°C. Homogenization can be carried out in a batch process or as a continuous process aided by rapid reaction kinetics. In some embodiments, one or more anti-solvents, such as heptane, octane, benzene, toluene, xylene, or another aprotic hydrocarbon, can be added to the solution to aid in the precipitation of one or more alkali metal by-products. In some embodiments, the anti-solvent is substantially miscible in the range of 7:1 v / v non-polar / polar to 1:2 v / v non-polar / polar. In another embodiment, at least 3:1 v / v non-polar / polar is used without affecting the solubility of one or more alkali metal sulfides or hydrosulfides. In further embodiments, additional amounts of ionic compounds, such as lithium-containing salts, to the polar organic solvent solution can further reduce the solubility of one or more by-products. The total amount of additional lithium-containing salt material can be 150% to 85% of stoichiometry to improve product purity and / or to include some amount of lithium-containing salt with one or more of the final lithium metal sulfides or hydrosulfides. For example, a well-mixed Li 2 The material product of combining S and LiCl is Li + , S -2 , Cl - The present invention is useful as a precursor for producing a sulfide solid electrolyte comprising:

[0164] The removal or separation of the one or more by-products may result from one or more separation methods, such as centrifugation, filtration, or gravity settling. These separation methods may be used separately or in combination to separate the alkali metal salt by-products from the mixture and isolate a supernatant containing one or more of highly soluble alkali metal hydrosulfides and lithium sulfides. In some embodiments, filtration may be performed after the initial double ion exchange reaction, after adding a certain amount of anti-solvent to the solution to precipitate additional amounts of the by-products.

[0165] Separation of the solvent from the supernatant to isolate lithium hydrosulfide and / or lithium sulfide may be accomplished by evaporating the solvent. Note that while the mixture may appear dry after the bulk solvent has been removed, it may contain solvent that constitutes as much as 75% of the total weight. It may be beneficial to utilize a solvent that has a low heat of vaporization, which uses less energy to remove. Additionally, the solvent may be recycled and reused.

[0166] After isolation of the desired lithium hydrosulfide and / or lithium sulfide, the remaining binding solvent may be removed prior to storage or use by heating in an inert atmosphere, such as argon or nitrogen, or under vacuum for a predetermined time and temperature. The temperature range is not limited and may range, for example, from 25°C to 900°C. In some embodiments, the temperature range may be from 200°C to 700°C. In other embodiments, the temperature range may be from 300°C to 500°C.

[0167] This heating process is 2 Sulfides containing S can be sintered. When synthesized, Li 2 S may have a particle size of less than 1 micron. 2 S is heated to a temperature of 300°C or higher, and then Li 2 The average particle size of S may be greater than 1 micron.

[0168] During heating of lithium hydrosulfide or a composite containing lithium hydrosulfide, the lithium hydrosulfide can decompose to lithium sulfide and release hydrogen sulfide gas, which can react with oxygen-containing species to convert them to sulfides or hydrosulfides.

[0169] Due to the decomposition of lithium hydrosulfide to hydrogen sulfide gas and lithium sulfide, the materials used to facilitate the reaction, such as the solvents and precursors used, may not need to be anhydrous. However, reducing the total amount of water entering the system may limit the production of undesirable oxide species. This is due to the fact that lithium sulfide is very soluble in water and hydrolyzes to lithium hydroxide releasing hydrogen sulfide gas. Lithium hydroxide has very low solubility in alcohols and other polar solvents. Therefore, if lithium hydroxide is formed during dissolution of the precursor, it may be removed from the system along with the alkali metal salt by-product when filtration or centrifugation is performed. This reduces the yield of the desired lithium sulfide. This problem can be avoided by slowing or preventing the formation of lithium hydroxide by lowering the temperature of the system. In some embodiments, the total amount of water entering the system may be less than 19 weight percent relative to the amount of lithium hydrosulfide used in the reaction. For example, one or more polar organic solvents may have a water content ranging from 0% to 5% by weight. In some embodiments, the water content is less than 1% by weight. In another embodiment, the water content is less than 0.1 wt%. In a further embodiment, the water content is less than 200 ppm. A water content ranging from 0 wt% to 10 wt% for one or more of the lithium-containing salt, the alkali metal hydrosulfide, and the alkali metal sulfide. In some embodiments, the water content is less than 5 wt%. In another embodiment, the water content is less than 1 wt%. In a further embodiment, the water content is less than 0.1 ppm%. In yet another embodiment, the water content is less than 500 ppm.

[0170] To further prevent the formation of undesirable oxide species, H 2Sulfur in the form of S or elemental sulfur can be introduced at various stages of the synthesis process. The sulfur can be partially or completely dissolved in the polar and / or non-polar solvent prior to the addition of the lithium-containing salt, sulfide precursor, or hydrosulfide material. The sulfur source may also be added to the solution containing the lithium-containing salt, the solution containing the hydrosulfide material, or both solutions. When elemental sulfur is used and added to the solution containing the sulfide material, Na 2 S x where X is greater than 1 but less than or equal to 10. Polysulfides may be formed, such as Na 2 S 5 Against Na 2 S), which may be less susceptible to hydrolysis. With increased solubility, the total amount of solvent used may be less than for its non-polysulfide counterpart. These polysulfides may also be formed by bubbling hydrogen sulfide gas through a solution of an alkali metal sulfide. However, when elemental sulfur is added to a solution containing a hydrosulfide material, the hydrosulfide material may decompose into hydrogen sulfide and its corresponding alkali metal sulfide material.

[0171] The introduction of the sulfur source may occur at any point during the drying or high temperature treatment of the lithium hydrosulfide or lithium hydrosulfide-lithium sulfide composite. When evaporating the solvent at high temperature under vacuum, elemental sulfur may be introduced by mixing, blending, or grinding. Due to the high volatility of elemental sulfur under high temperature, low pressure conditions, elemental sulfur may need to be added in excess of what is needed to reduce any undesirable oxide species. In some embodiments, the amount of sulfur added may be 100% or less of the weight of the lithium hydrosulfide or mixture of lithium hydrosulfide and lithium sulfide. In another embodiment, the amount of sulfur added may be 50% or less of the weight of the lithium hydrosulfide or mixture of lithium hydrosulfide and lithium sulfide. In a further embodiment, the amount of sulfur added may be 25% or less of the weight of the lithium hydrosulfide or mixture of lithium hydrosulfide and lithium sulfide. In yet another embodiment, the amount of sulfur added may be 10% or less of the weight of the lithium hydrosulfide or mixture of lithium hydrosulfide and lithium sulfide. In further embodiments, the amount of sulfur added may be 5% or less by weight of the lithium hydrosulfide or the mixture of lithium hydrosulfide and lithium sulfide. The composite containing sulfur and lithium hydrosulfide can then be heated to a desired temperature at which the sulfur melts or sublimes, aiding in the removal of the solvent and converting any oxygen-containing compounds to metal sulfides.

[0172] For purposes of this disclosure, the term "substantially" refers to a condition that is near (including) 100% of a parameter. By way of example, near 100% can range from about 80% to 100%, from about 90% to 100%, or from about 95% to 100%.

[0173] FIG. 1 shows the Li synthesized in Examples 1 to 4 and Comparative Example. 2 The figure shows the X-ray diffraction of the S material. From this figure, it can be seen that all of Examples 1 to 4 are >80% Li 2 S purity, and two of these examples, Examples 1 and 2, have a purity of >90% Li 2 S purity, and Example 1 has a purity of >95% Li 2It can be shown to have a purity of Li 2 The amount of LiCl present in the S mixture can be reduced by manipulating the molar ratio of lithium-containing to sodium-containing species. The amount of NaCl present in the composite can be reduced by modifying the process used to remove NaCl, for example by further incorporating one or more techniques such as centrifuges, filters, cooling the mixture, and the addition of flocculants. 3 The amount of oxyhalide species such as ClO is 2 NaHS, used in the synthesis of S 2 It can be further reduced by increasing the ratio of Li to S. 3 Oxyhalide species such as ClO, or Li 2 CO 3 , Li 2 SO 4 , Li 2 The amount of O, or other oxygen-containing species such as LiOH, may vary depending on the synthesis process, drying, or the resulting Li 2 During one or more steps of the heat treatment of the S mixture, H 2 These changes can reduce or eliminate the production of Li at 99% purity or higher. 2 It is possible to manufacture S.

[0174] [Table 1]

[0175] FIG. 2 shows the results of Li prepared in Example 3, Example 4, and Comparative Example 1. 2 1 shows the thermogravimetric analysis (TGA) of the LiS material produced according to these examples and comparative examples. 2 The LiS material was heated to 200° C. under vacuum for 1 hour. The material was placed in a TGA with an argon flow and the Li 2 The S material was heated to 450°C at a rate of 5°C / min.

[0176] Li 2S, NaCl, and NaS 2 O 3 Further provided herein is a composition produced by the method of the present disclosure, comprising: 2 S (2θ = 27°, 31.3°), NaCl (31.7°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°).

[0177] Li 2 S, LiCl, and NaS 2 O 3 Further provided herein is a composition produced by the method of the present disclosure, comprising: 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°).

[0178] Li 2 S, LiCl, and NaS 2 O 3 Further provided herein is a composition produced by the method of the present disclosure, comprising: 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°).

[0179] Li 2 S, LiCl, and Li 3Further provided herein is a composition produced by the method of the present disclosure comprising OCl. The composition has an x-ray diffraction spectrum shown in FIG. 4, labeled Example 8. The peaks in the x-ray diffraction spectrum are Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Li 3 Corresponding to OCl (22.8°, 32.5°, 40°).

[0180] Li 2 S., Li 2 Further provided herein is a composition produced by the disclosed method comprising: O, and LiOH. The composition has an x-ray diffraction spectrum shown in FIG. 4, labeled Example 9. The peaks in the x-ray diffraction spectrum are Li 2 S (2θ = 27°, 31.3°), LiOH (20.5°, 32.6°, 35.7°), NaCl (31.7°), and Li 2 O(33.7°).

[0181] NaLiS, Na 2 S 2 , Na 2 S, LiCl, NaHS, Li 2 S, and Na 2 S 2 O 3 Further provided herein is a composition produced by the method of the present disclosure, comprising: 2 S 2 (2θ=23.3°, 28.8°, 31.9°, 40°, 40.9°), Na 2 S (23.6°, 39°, 46.1°), NaLiS (26°, 27.4°, 31.4°, 35.5°), and NaSH (30.3°, 40.3°).

[0182] Li 2 S., Li 2Further provided herein is a composition produced by the disclosed method, comprising: O, LiOH, LiCl, NaLiS, and NaCl. The composition has an x-ray diffraction spectrum shown in FIG. 5, labeled Example 11. The peaks in the x-ray diffraction spectrum are NaLiS (2θ=26°, 27.4°, 31.4°, 35.5°), LiOH (20.5°, 32.6°, 35.7°), and Li 2 O(33.7°).

[0183] Li 2 S., Li 3 Further provided herein is a composition produced by the method of the present disclosure, comprising OCl, LiCl, and NaCl. The composition has an x-ray diffraction spectrum shown in FIG. 5, labeled Example 12. The peaks in the x-ray diffraction spectrum are Li 2 S(2θ=27°, 31.3°), LiCl(30°, 34.8°), Li 3 Corresponding to OCl (22.8°, 32.5°, 40°), and NaCl (31.7°).

[0184] Li 2 S, Na 2 S 2 , NaLiS, and β-Na 2 Further provided herein is a composition produced by the method of the present disclosure comprising S. The composition has an x-ray diffraction spectrum shown in FIG. 5, labeled Example 13. The peaks in the x-ray diffraction spectrum are Li 2 S (2θ = 27°, 31.3°), NaLiS (26°, 27.4°, 31.4°, 35.5°), and β-Na 2 Compatible with S (24.6°, 28.9°, 35.1°, 40.4°).

[0185] Here, the present disclosure is illustrated with examples, which are intended to illustrate the present disclosure and are not intended to limit any limitations on the technical scope of the present disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. EXAMPLES

[0186] Example 1

[0187] 0.667 grams of sodium anhydrous 2 S and 0.718 grams of anhydrous NaHS were dissolved in 16 grams of anhydrous ethanol with less than 50 ppm water, and separately, about 1.09 grams of anhydrous LiCl (stoichiometric amount) was dissolved in 6 grams of anhydrous ethanol with less than 50 ppm water. The LiCl solution was then dissolved in Na at approximately room temperature (25° C.). 2 The mixture was cooled to -25°C and then centrifuged at 4000 rpm for 10 min to separate the supernatant, which contained mainly Li in the alcohol. 2 The resulting mixture contained 1,000 S and LiHS, and removed the insoluble NaCl by-product. At this point, most of the alcohol was removed from the supernatant using a rotary evaporator at 200° C. under vacuum. At this stage, the material appeared dry but contained about 15% bound solvent. The product was further heat treated at 400° C. under argon for 1 hour. This step removed the residual solvent and converted the LiHS to Li 2 S is converted to hydrogen sulfide gas, releasing Li 2 It was useful for sintering S on a microscale.

[0188] Example 2

[0189] Na 2 The experiment was carried out in the same manner as in Example 1, except that 0.75 g of S, 0.479 g of NaHS, and 1.09 g of LiCl were used.

[0190] Example 3

[0191] Na 2 The experiment was carried out in the same manner as in Example 1, except that 0.8 g of S, 0.359 g of NaHS, and 1.09 g of LiCl were used.

[0192] Example 4

[0193] Na 2 The experiment was carried out in the same manner as in Example 1, except that 0.9 g of S, 0.144 g of NaHS, and 1.09 g of LiCl were used.

[0194] Comparative Example 1

[0195] Na 2 The experiment was carried out in the same manner as in Example 1, except that 1.0 g of S, 0.00 g of NaHS, and 1.09 g of LiCl were used.

[0196] Experimental Results

[0197] According to Table 1 and FIG. 1, it can be shown that a process of dissolving an alkali metal salt precursor, a sulfide precursor compound, and a hydrosulfide precursor compound in one or more polar solvents in which there is a solubility difference between the alkali metal sulfide and the alkali metal salt by-products and between the alkali metal hydrosulfide and the alkali metal salt by-products can form a mixture containing soluble lithium sulfide, soluble lithium hydrosulfide, and precipitated alkali metal salt by-products. From this mixture, lithium sulfide is isolated by removing the alkali metal salt by-products and evaporating the polar solvent to form a mixture containing lithium sulfide and lithium hydrosulfide, which is further heated to convert the lithium hydrosulfide to lithium sulfide. When lithium hydrosulfide reaches a decomposition temperature of about 200° C., the material decomposes to form lithium sulfide and hydrogen sulfide gas. At temperatures of at least 200° C., this hydrogen sulfide gas can help remove residual solvent that may cause the formation of undesirable materials.

[0198] Table 1 shows that by increasing the amount of hydrosulfide material present, the amount of undesirable oxide species, such as LiOCl, can be reduced or eliminated. For example, comparing Example 4 with Comparative Example 1, 2 It can be shown that the 22.2% molar substitution of S with NaHS reduces the amount of LiOCl present in the final product from 18.8 wt% to 8.3 wt%, a reduction of more than 55%. 2It can be shown that by making a 50% molar substitution of S with NaHS, the amount of LiOCl present in the final product is reduced from 18.8 wt% to 2.5 wt%, a reduction of more than 86%. This results in a final lithium sulfide material with a purity of 95.2%. Higher purity lithium sulfide materials can be produced by further increasing the amount of alkali metal hydrosulfide incorporated into the process.

[0199] As can be seen from FIG. 2, the Li produced in Comparative Example 1 2 It can be seen that the LiS material exhibited a mass loss of 13.12% when heated to 450°C at 5°C / min in the TGA after heating at 200°C for 1 hour under vacuum. The majority of the mass loss began at about 340°C, with the Li 2 This may be due to the removal of the organic solvent in the S mixture. 2 After heating the S material at 200°C for 1 hour under vacuum, 2 The LiS material exhibited a mass loss of 9.35% when heated to 450 °C at 5 °C / min in the TGA. Part of this mass loss began at about 345 °C, with the Li 2 This is believed to be due to the decomposition of the organic solvent bonded to the LiS material. 2 When the S material was heated in vacuum at 200°C for 1 hour and then heated to 450°C at 5°C / min in GA, the Li 2 The LiS material showed a mass loss of 7.5%. A small portion of this mass loss began near 360 °C, with the Li 2 This data and the information in Table 1 indicate that the amount of final LiS increases with increasing amounts of alkali metal hydrosulfide used in this synthesis method. 2 It can be shown that the overall amount of oxide species present in the S product is reduced. Specifically, Comparative Example 1, which did not use an alkali metal hydrosulfide in the synthesis, had a mass loss of 13.12% in the TGA, with 18.8% Li 3 Example 4 contains Na 2 The NaHS was incorporated to give a molar ratio of 9:2 S:NaHS, with a mass loss of 9.35% and 8.4% Li3 In Example 3, mass loss and Li 3 The OCl content is further reduced by increasing the hydrosulfide content in the synthesis. In this example, NaHS is mixed with Na in a 4:2 molar ratio. 2 S:NaHS, with a mass loss of 7.5% and 3.4% Li 3 Contains OCl.

[0200] Example 5 16 g of ethanol was added to a 20 mL vial containing a small magnetic stir bar. 0.8717 g of anhydrous LiCl was added to ethanol and the solution was stirred and heated to 78° C. After 15 minutes, 0.313 g of NaSH containing 24% water by weight in the form of hydrate and 0.666 g of Na containing less than 300 ppm water were obtained. 2 The mixture with S was added to the hot ethanol-LiCl solution and a precipitate formed almost immediately. The mixture was then stirred overnight (16-18 hours) while being kept at a constant temperature of 78°C. After 16-18 hours, the mixture was poured into a centrifuge tube and placed in a -25°C freezer for about 1 hour to encourage more precipitation. After about 1 hour, the mixture was centrifuged at 4000 rpm for 10-15 minutes and then returned to the -25°C freezer for another 30 minutes. After 30 minutes, the mixture was centrifuged for an additional 5 minutes and then returned to the -25°C freezer for at least 30 minutes. After 30 minutes, the mixture was poured into an evaporating flask. The filtered solution was then heated to a temperature of about 250°C under vacuum conditions for about 1 hour. The dried solid was then heated to a temperature of about 450°C for about 15 minutes.

[0201] The material produced in Example 5 was 94.4% Li 2 S, 3.9% NaCl, and 1.7% Na 2 S 2 O 3 The x-ray diffraction pattern of the material is shown in Figure 3. The x-ray diffraction measurement was performed at Cu-Kα(1,2) = 1.54064 Å. The XRD spectrum of the material produced by Example 5 shows Li 2S (2θ = 27°, 31.3°), NaCl (31.7°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°) evidence.

[0202] Surprisingly, NaHS H, which contains 24% water by mass, 2 Using O material, 94.4% purity Li 2 S material was produced. In addition, NaCl and Na 2 SO 3 Li is not very soluble in alcohol. Therefore, these impurities are not easily absorbed by Li with a purity of 99% or more. 2 It is believed that improved filtration techniques can be used to remove the S compounds resulting in the S compounds.

[0203] Example 6

[0204] Example 6 uses precursor amounts of 15.024 g NaHS containing 24 wt. % water, 31.968 g NaHSO containing 300 ppm water, 2 The same procedure as in Example 5 was carried out, except that the amount of ethanol used was increased to 1000 ml, and the amount of ethanol used was increased to 52 g.

[0205] The material produced in Example 6 was 77% Li 2 S, 21.1% LiCl, and 1.9% Na 2 S 2 O 3 Li-containing complex 2 The XRD spectrum of the material produced by Example 6 shows that the material is LiS-LiCl. The XRD pattern of the material is shown in FIG. 3. The XRD measurement was performed at Cu-Kα(1,2)=1.54064 Å. The XRD spectrum of the material produced by Example 6 shows that the material is Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°) evidence.

[0206] Importantly, the complex Li 2 The S-LiCl material is Li 3 It is formed without the formation of OCl, which is Na 2 This is not possible if only S is used.

[0207] Example 7

[0208] Example 7 was carried out in the same manner as Example 5, except that anhydrous LiCl was used in an amount of 1.2 g. The material produced in Example 7 contained 66% Li 2 S, 33% LiCl, and 1% Na 2 S 2 O 3 Li-containing complex 2 The XRD spectrum of the material produced by Example 7 shows that the material is LiS-LiCl. The XRD pattern of the material is shown in FIG. 3. The XRD measurement was performed at Cu-Kα(1,2)=1.54064 Å. The XRD spectrum of the material produced by Example 7 shows that the material is Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 (21.5°, 24.2°, 27.5°, 29°, 41.8°) evidence.

[0209] Importantly, the complex Li 2 The S-LiCl material is Li 3 It is formed without the formation of OCl, which is Na 2 This is not possible when only S is used. For comparison, Li 3 See Example 8 below, where OCl was formed. This example also demonstrates the relative amount of Li relative to LiCl by adjusting the amount of each precursor used in the reaction. 2 Demonstrate that the ratio of S can be adjusted.

[0210] Example 8

[0211] Example 8: 1.5 g of NaSH·3H containing approximately 50% water by mass 2 O and 0.4950 g of NaSH H containing 24% water by mass.2 The same procedure was followed as in Example 5, except that 0 was used. In addition, the amount of LiCl used was increased to 1.0896 g. The total amount of water introduced into the reaction was 1.005 g, and the weight ratio of NaSH to total water was 0.49:1. The weight ratio of NaSH to LiCl was 0.45:1. The material produced in Example 8 had a Li content of 47.5%. 2 S, 34.2% LiCl, and 16.1% Li 3 The XRD spectrum of the material produced by Example 8 shows Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Li 3 Showing evidence of OCl (22.8°, 32.5°, 40°).

[0212] Example 9

[0213] Example 9 is 2.0 g of NaSH·3H containing approximately 50% water by weight. 2 O and 0.660 g of NaSH H containing 24% water by mass. 2 The reaction was carried out as in Example 8, except that 1.345 g of water was used. The weight ratio of NaSH to total water was 0.49:1. The weight ratio of NaSH to LiCl was 0.6:1. The material produced in Example 9 was 78.4% Li 2 S, 9.4% Li 2 The XRD spectrum of the material produced according to Example 9 shows Li 2 S (2θ = 27°, 31.3°), LiOH (20.5°, 32.6°, 35.7°), NaCl (31.7°), and Li 2 Evidence of O(33.7°) is shown.

[0214] Example 10

[0215] In Example 10, NaSH·3H containing about 50% by mass of water was used. 2 O4.3664g and NaSH H containing 24% water by mass 2 The reaction was carried out as in Example 8, except that 0.1.4409 g of O was used. The total amount of water introduced into the reaction was 2.9255 g, and the weight ratio of NaSH to total water was 0.49:1. The weight ratio of NaSH to LiCl was 1:0.76. The material produced in Example 10 was 82.1% NaLiS, 8.8% Na 2 S 2 , and 3.6% Na 2 S, 1.8%LiCl, 1.5%NaHS, 1.2%Li 2 S, and 1% Na 2 S 2 O 3 The x-ray diffraction patterns of the material are shown in Figures 4 and 5. The x-ray diffraction measurements were performed at Cu-Kα(1,2)=1.54064 Å. The XRD spectrum of the material produced by Example 10 shows Na 2 S 2 (2θ=23.3°, 28.8°, 31.9°, 40°, 40.9°), Na 2 Showing evidence of S (23.6°, 39°, 46.1°), NaLiS (26°, 27.4°, 31.4°, 35.5°), and NaSH (30.3°, 40.3°).

[0216] Example 11

[0217] Example 11 is 4.3664 g of NaSH·3H containing 54% water by weight. 2 0 was added to 0.313 g of NaSH H 2 0.9517 g Na2S xH 2 O, and 0.2746 g Na containing 300 ppm water 2 The same procedure was followed as in Example 10, except that 57% Li was replaced by 57% S. The total amount of water introduced into the reaction was 0.48 g, and the weight ratio of NaSH to total water was 0.49:1. The material produced in Example 11 was 57% Li 2 S, 17.9% Li 2The composition of the material was 19.5% LiOH, 3.4% NaLiS, 1.1% NaCl, and 1.1% others. The x-ray diffraction pattern of the material is shown in Figure 5. The x-ray diffraction measurements were performed at Cu-Kα(1,2) = 1.54064 Å. The XRD spectrum of the material produced by Example 11 was 100% NaLiS (2θ = 26°, 27.4°, 31.4°, 35.5°), LiOH (20.5°, 32.6°, 35.7°), and Li 2 Evidence of O(33.7°) is shown.

[0218] Example 12

[0219] Example 12 was carried out in the same manner as Example 10, except that two changes were made. First, 4.3664 g of NaSH·3H containing 54% water by weight was added. 2 0 was mixed with 0.313 g of NaSH HO containing 24 wt% water and 0.666 g of Na 2 S was substituted. Then, 0.56 ml of DI water was added to the ethanol before synthesis. The total amount of water introduced into the reaction was 0.48 g, and the weight ratio of NaSH to total water was 0.49:1. The material produced in Example 12 was 79.6% Li 2 S, 18.6% Li 3 The XRD spectrum of the material produced according to Example 12 was Li 2 S(2θ=27°, 31.3°), LiCl(30°, 34.8°), Li 3 Showing evidence of OCl (22.8°, 32.5°, 40°), and NaCl (31.7°).

[0220] Example 13

[0221] 1.8959 g of NaSH H containing 24% water by mass 2 Mix 1 mL of HO with 0.27 mL of deionized water and dilute the hydration solution to 1–2 mL (NaSH 2HO). 2Example 13 was carried out in the same manner as Example 10, except that the NaSH was adjusted to 68% LiO. This freshly hydrated NaSH was then used to replace 4.3664 g of NaSH containing 54% water by weight. The total amount of water introduced into the reaction was 0.725 g, and the weight ratio of NaSH to total water was 1:0.5. The material produced in Example 13 was 68% Li 2 S, 15.4%Na 2 S 2 , 13.2% NaLiS, and 3.3% β-Na 2 The XRD spectrum of the material produced by Example 13 shows Li 2 S (2θ = 27°, 31.3°), NaLiS (26°, 27.4°, 31.4°, 35.5°), and β-Na 2 Showing evidence of S (24.6°, 28.9°, 35.1°, 40.4°).

[0222] In both Example 11, where water was introduced in the form of sulfide hydrates, and Example 12, where water was introduced in the form of an ethanol-water solvent blend to simulate aqueous conditions, lithium-oxygen-containing species (Li 2 O, LiOH, Li 3 In contrast to these, in Example 13, water was added directly to the NaSH material, resulting in a material that was substantially free of oxides, resulting in the formation of hydrosulfide hydrates. It was therefore concluded that water can be introduced into the system with the formation of hydrosulfide hydrates to produce a material that is substantially free of oxides.

[0223] Example 14

[0224] 1.1469 g of technical grade LiCl (95% LiCl, 2.5% MgCl 2 , 2.5% CaCl 2 Example 14 was carried out in the same manner as Example 5, except that technical grade LiCl was used, 3.8 g LiCl, 0.1 g MgCl 2, and 0.1 g of CaCl2, resulting in a composite of 95 wt.% LiCl, 2.5 wt.% MgCl2. 2 %, and 2.5 wt.% CaCl 2 The materials were mixed manually using a mortar and pestle. The material from Example 14 was 63.3% Li 2 S, 34.8% LiCl, and 1.8% Na 2 S 2 O 3 The x-ray diffraction patterns of the material prepared in Example 14 and technical grade LiCl are shown in Figure 6. The x-ray diffraction measurements were performed at Cu-Kα(1,2)=1.54064 Å. The XRD spectrum of the material prepared by Example 14 shows that Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Na 2 S 2 O 3 The XRD spectrum of the technical grade LiCl material shows evidence of LiCl (2θ = 30°, 34.8°), MgCl 2 (29.3°, 30.5°, 38.7°), and CaCl 2 (19.8°, 29.3°, 38.6°, 40.2°) evidence.

[0225] Technical grade LiCl material contains contaminants that are typically found in what is referred to in the industry as technical grade LiCl. These MgCl 2 and CaCl 2 The impurities are difficult to remove and require specialized ion exchange systems to remove, which is a product of the high solubility of the impurities in polar solvents such as water and alcohol. The disclosed method uses highly soluble MgCl 2 and CaCl 2The impurities are converted to their corresponding sulfides, MgS and CaS, which are practically insoluble in alcohol. Due to their low solubility in ethanol, these impurities can be removed by filtration. Thus, a relatively low purity LiCl can be used to produce LiCl free of such Mg- and Ca-containing impurities. 2 S material or Li 2 S-LiCl compounds can be produced.

[0226] Example 15

[0227] In Example 15, the mass of the precursor was 0.1569 g of NaHS containing 24 wt.% water, 0.333 g of Na containing 300 ppm water, 2 The same procedure was carried out as in Example 5, except that 0.2 g of industrial grade Li was added, and 0.5448 g of anhydrous LiCl was added. 2 S(91%Li 2 S, 4.5% Li 2 SO 4 , and 4.5% Li 2 CO 3 ) was added to ethanol along with NaHS and Na2S. 2 S, Li 2 SO 4 and Li 2 CO 3 and 91% by weight Li 2 S, 4.5% weight Li 2 SO 4 and 4.5% by weight Li 2 CO 3 By mixing in the ratio of industrial grade Li 2 S was prepared. The materials were mixed manually using a mortar and pestle.

[0228] Example 15 and technical grade Li 2 The x-ray diffraction pattern of the material produced by Example 15 is shown in FIG. 7. The x-ray diffraction measurement was performed at Cu-Kα(1,2)=1.54064 Å. The XRD spectrum of the material produced by Example 15 shows that Li 2 S (2θ = 27°, 31.3°), LiCl (30°, 34.8°), and Li 3Shows evidence of OCl (22.8°, 32.5°, 40°). Technical grade Li 2 The XRD spectrum of the S material is Li2S (2θ = 27°, 31.3°), Li 2 CO 3 (21.3°, 23.5°, 29.5°, 30.6°, 31.8°, 34.1°, 36.1°, 37°, 39.5°, 39.9°), and Li 2 SO 4 (22.4°, 26°, 37°). 2 CO 3 and Li 2 SO 4 The absence of lithium-oxygen species is consistent with industrial grade Li 2 It is demonstrated that S can be introduced into the reaction and removed from the final product.

[0229] Example 16

[0230] Li prepared in Example 6 2 S-LiCl complex 11.1051g, P 2 S 5 A precursor containing 8.2902 g of ZnO (Sigma-Aldrich) and 0.7157 g of LiCl (Sigma-Aldrich) was added to a 250 ml zirconia milling jar containing zirconia milling media and a compatible solvent (e.g., xylene or heptane). The mixture is milled in a Retsch PM100 planetary mill at 500 RPM for 12 hours. The material is recovered and dried in an inert (argon or nitrogen) environment at 140 °C for 2 hours. The resulting solid electrolyte powder (Li 6 P.S. 5 Cl) was heated to a temperature of about 400° C. for about 30 minutes.

[0231] The x-ray diffraction pattern of the material prepared in Example 16 is shown in Figure 8. The x-ray diffraction measurements were performed at Cu-Kα(1,2)=1.54064 Å.

[0232] The ionic conductivity of this material at room temperature (25° C.) was 2.2 mS.

[0233] These results demonstrate that sulfide solid electrolytes with high ionic conductivity (i.e., greater than 2 mS) can be produced by the methods described herein with Li 2 This demonstrates that it can be synthesized using the S-LiCl complex.

[0234] Example 17

[0235] Thermogravimetric analysis (TGA) was performed to compare the material synthesized in Example 5 with the material synthesized in Comparative Example 1. The TGA data labeled Example 5 was obtained by taking an aliquot of the material from Example 5 and heating it to below 100° C. for 1 hour. The material was then placed in the TGA and heated to 450° C. at a ramp rate of 5° C. / min. The TGA data labeled Comparative Example 1-100° C. was obtained by taking an aliquot of the material from Comparative Example 1 and heating it to below 100° C. for 1 hour. The material was then placed in the TGA and heated to 450° C. at a ramp rate of 5° C. / min. The TGA data labeled Comparative Example 1-250° C. was obtained by taking an aliquot of the material from Comparative Example 1 and heating it to below 250° C. for 1 hour. The material was then placed in the TGA and heated to 450° C. at a ramp rate of 5° C. / min. The data is shown in FIG. 9. The material labeled Comparative Example 1-100°C had a mass loss of 43.9%, the material labeled Comparative Example 1-250°C had a mass loss of 19.66%, and the material labeled Example 5 had a mass loss of 8.0%.

[0236] By comparing Example 5 with Comparative Example 1-100°C, NaSH xH 2 When using hydrate hydrosulfide raw materials such as O, Na 2 It can be demonstrated that the solvent such as ethanol can be removed at a lower temperature compared to the synthesis using only metal sulfide such as S. Specifically, both Example 5 and Comparative Example 1-100°C were heated under the same conditions (100°C), but Example 5 had only 8% mass loss, and Comparative Example 1-100°C had 43.9% mass loss. This is because the amount of Li 2This corresponds to an 82% reduction in the amount of solvent bound to the S material. Removal of the solvent at lower temperatures reduces the likelihood of forming oxygen or carbon containing species.

[0237] FIG. 10 shows FTIR spectra of materials produced in Example 5 and Comparative Example 1. The top spectrum (red) was obtained by taking a divided portion of Comparative Example 1 and heating it to below 100° C. The second spectrum from the top (green) was obtained by taking a divided portion of Example 5 and heating it to below 100° C. The third spectrum from the top (purple) was obtained by taking a divided portion of Example 5 and heating it to below 250° C. The third spectrum from the top (purple) was obtained by taking a divided portion of Example 5 and heating it to below 200° C.

[0238] The features described above, as well as those claimed below, can be combined in various ways without departing from the scope of the present specification. The previous examples show some possible non-limiting combinations. Therefore, it should be noted that the matters contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not limiting. Thus, many combinations, substitutions, variations, and modifications of the foregoing embodiments of the disclosure that are not expressly described herein, nevertheless fall within the scope of such disclosure.

Claims

1. 1. A method for producing a water-reactive alkali metal sulfide, comprising: (a) reacting a first alkali metal salt and a first alkali metal hydrosulfide, and optionally a first sulfide, in a polar solvent to produce a mixture containing a second sulfide and a second alkali metal salt precipitate; (b) removing the precipitated second alkali metal salt from the mixture to produce a supernatant comprising the second sulfide and the polar solvent; and (c) removing the polar solvent from the supernatant; A method comprising:

2. 10. The method of claim 1, wherein removing the polar solvent from the supernatant comprises evaporating the polar solvent to produce a powder.

3. The method of claim 2 , wherein the evaporating comprises drying the powder to remove substantially all of the polar solvent.

4. 4. The method of any one of claims 1 to 3, wherein removing the polar solvent from the supernatant comprises spray drying, rotary drying, tray drying, fluidized bed drying, vacuum drying, or a combination thereof.

5. 4. The method of claim 1, further comprising adding a sulfur source to increase the purity of the second sulfide.

6. The sulfur source comprises elemental sulfur and H ２ 6. The method of claim 5, comprising one or more of: S.

7. The method of any one of claims 1 to 3, wherein the supernatant further comprises a second alkali metal hydrosulfide.

8. further comprising introducing an antisolvent to the supernatant prior to or immediately after precipitation of the second alkali metal salt; the anti-solvent is selected from the group consisting of a hydrocarbon solvent, a non-polar solvent, a solvent that is substantially miscible in the polar solvent, a solvent that increases the difference in solubility of one or more of the second sulfide and the second alkali metal hydrosulfide compared to the second alkali metal salt in the polar solvent, and combinations thereof; The method according to any one of claims 1 to 3.

9. 4. The method of claim 1, wherein the removal of the second alkali metal salt from the supernatant is by at least one of centrifugation, filtration, gravity settling, and cooling.

10. 4. The method of claim 1, further comprising reducing the amount of the polar solvent from the supernatant, wherein reducing comprises at least one of evaporating the polar solvent, heating the polar solvent, or reducing the ambient atmospheric pressure surrounding the supernatant.

11. 4. The method of any one of claims 1 to 3, comprising increasing the relative amounts of the first alkali metal salt, the first sulfide compound, if present, or the first alkali metal hydrosulfide compound to increase the purity of the second sulfide to greater than 95 wt%.

12. The method according to any one of claims 1 to 3, wherein the polar solvent or the first alkali metal hydrosulfide is substantially anhydrous.

13. The method according to any one of claims 1 to 3, wherein the mass ratio of the first alkali metal hydrosulfide to the water incorporated therein is greater than 2:1, greater than 3:1, or greater than 4:

1.

14. The first alkali metal salt comprises LiCl, the first alkali metal hydrosulfide comprises NaHS, the first sulfide is present, and Na ２ The method of any one of claims 1 to 3, comprising S.

15. The second alkali metal salt comprises NaCl, and the second sulfide comprises Li ２ The method of any one of claims 1 to 3, comprising S.

16. 4. The method of any one of claims 1 to 3, wherein the first alkali metal salt and, if present, the first sulfide are dissolved separately in separate portions of the polar solvent, and the separate portions are combined to form a mixture prior to addition to the first alkali metal hydrogen sulfide.

17. 4. The method of any one of claims 1 to 3, wherein the first alkali metal salt, the first sulfide compound, if present, and the first alkali metal hydrosulfide are independently dissolved in the polar solvent before reacting them together.

18. 4. The method of claim 1, wherein one of the first alkali metal salt, the first sulfide, if present, and the first alkali metal hydrosulfide is dissolved in the polar solvent, and the others are added to the solution in solid form.

19. The method of any one of claims 1 to 3, wherein the ratio of the solubility of the second sulfide to the solubility of the second alkali metal salt in the polar solvent is 90:10, 97:3, 99:1, or 99.1:0.

1.

20. The first sulfide compound is present, and K ２ S, Na ２ S, (NH4) ２ The method of any one of claims 1 to 3, wherein the hydroxybenzoate is selected from the group consisting of hydroxybenzoates, ...

21. 4. The method of claim 1, wherein the first alkali metal hydrosulfide compound is selected from the group consisting of KHS, NaHS, LiHS, and mixtures thereof.

22. The second sulfide is Li ２ The method of any one of claims 1 to 3, comprising S.

23. The method of any one of claims 1 to 3, wherein the resulting mixture further comprises LiNaS, Li 2 MgS 2 , or Li 2 CaS 2 .

Images