Method for producing water-reactive sulfide materials

Abstract

A method for producing a low-cost, water-reactive alkali metal sulfide material includes dissolving a substantially anhydrous alkali metal salt and a substantially anhydrous sulfide precursor compound in a substantially anhydrous polar solvent that provides a solubility differential for the substantially highly soluble alkali metal sulfide and the substantially less soluble by-products to form a mixture of the highly soluble alkali metal sulfide and the less soluble by-products; separating the less soluble by-products from the mixture to isolate a supernatant containing the alkali metal sulfide; and separating the polar solvent from the alkali metal sulfide to produce the alkali metal sulfide. The present invention provides a scalable method for producing high-purity alkali metal sulfides that are substantially free of undesirable by-products.

Description

Technical Field

[0001] Related Applications This application claims the priority of U.S. Provisional Patent Application No. 62 / 977,505 filed on February 17, 2020, and U.S. Provisional Patent Application No. 63 / 140,624 filed on January 22, 2021. The entire contents of these are incorporated herein by reference, respectively.

[0002] The various embodiments described in this disclosure relate to the field of manufacturing alkali metal sulfide compounds that can be used in solid primary and secondary electrochemical cells, electrodes and electrode materials, electrolytes and electrolyte compositions.

Summary of the Invention

Means for Solving the Problems

[0003] In one embodiment, a method for manufacturing a water-reactive metal sulfide compound is dissolving a substantially anhydrous alkali metal salt and a substantially anhydrous sulfide compound in a polar organic solvent that provides a solubility difference for the highly soluble alkali metal sulfide and the low solubility by-product to form an anhydrous solution; causing a chemical reaction to form a supernatant of the highly soluble alkali metal sulfide dissolved in the polar solvent and a precipitate of the low solubility by-product; separating the low solubility by-product from the supernatant and evaporating the polar solvent from the supernatant; and performing a final heat treatment to isolate the alkali metal sulfide; including.

[0004] This disclosure can be understood by referring to the following detailed description in connection with the drawings briefly described below.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Examples 1, 2, and 3.

[0006] [Figure 2] Figure 2 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Examples 4 and 5.

[0007] [Figure 3] Figure 3 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Example 6. [Figure 4] Figure 4 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Example 7. [Figure 5] Figure 5 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Example 8. [Figure 6] Figure 6 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Example 9. [Figure 7] Figure 7 shows the X-ray diffraction pattern of lithium sulfide (Li2S) synthesized in Example 10. [Modes for carrying out the invention]

[0008] The following description provides specific details so that various embodiments of the present invention may be fully understood. However, by reading and understanding the specification, claims and drawings, those skilled in the art will understand that some embodiments of the present invention can be carried out without following some of the specific details shown in this disclosure. Furthermore, to avoid ambiguity of the present invention, some well-known methods, processes, apparatus and systems in the various embodiments described in this disclosure are not disclosed in detail.

[0009] Alkali metal sulfides, such as lithium sulfide (Li2S), are an important class of materials useful in solid primary and secondary electrochemical cells, electrodes and electrode materials, electrolytes and electrolyte compositions, and ultimately in larger systems that utilize such components, such as computers, drones, and electric vehicles. Today, the most common applications of Li2S are as a precursor material for manufacturing sulfide solid electrolytes and as an active cathode material for lithium-sulfur batteries. To support the continued and increasing use of alkali metal sulfides, this disclosure describes improvements for manufacturing alkali metal sulfides at a lower cost using a higher purity and scalable process. The process described in this disclosure enables low-cost, high-purity metal sulfides, such as Li2S, which for the first time enable cost-effective sulfide-based solid electrolytes, solid-state batteries, and solid-state battery-powered vehicles.

[0010] Reactive and ionic alkali metal sulfides generally do not exist as naturally occurring minerals due to their solubility and tendency to spontaneously hydrolyze. Many methods are known for synthesizing alkali metal sulfides, but these generally result in variations in purity and composition, or involve expensive and toxic substances and complex processes. One known method is the reduction of alkali metal sulfates with organic compounds, carbon, or hydrogen in an inert or reducing atmosphere (Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry). This method has the disadvantage of difficulty in avoiding unreacted products due to insufficient mixing, and difficulty in separating excess carbon without hydrolyzing the product. Smith (U.S. Patent No. 3642436) teaches the reaction of alkali metals with hydrogen sulfide or sulfur vapor, but this method requires relatively expensive Li metal and handling large quantities of hydrogen sulfide, a highly toxic and flammable gas. Mehta (U.S. Patent No. 6,555,078) teaches a reaction of a lithium salt with a sodium salt of the desired anion in an aqueous or semi-aqueous solution, but this process is not suitable for water-reactive alkali metal sulfides because it results in partial hydrolysis of the resulting material. Barker (U.S. Patent No. 8,377,411) teaches a high-temperature synthesis of alkali metal carbonates or hydroxides using sulfur vapor. The drawback of this method is the corrosion of processing equipment at the required high temperatures. Dawidowski (German Patent Application Publication No. 102012208982) teaches a reaction of a lithium metal base with a hydrogen sulfide in an organic solvent, but this method uses expensive lithium organic compounds as precursors.

[0011] The present invention provides a process for producing a water-reactive alkali metal sulfide material, comprising: dissolving a substantially anhydrous alkali metal salt and a substantially anhydrous sulfide precursor compound in a substantially anhydrous organic polar solvent that provides a solubility difference between a substantially highly solubility alkali metal sulfide and a substantially less solubility by-product, thereby forming a mixture of a highly solubility alkali metal sulfide and a less solubility by-product; separating the less solubility by-product from the mixture to isolate the supernatant containing the alkali metal sulfide; and separating the polar solvent from the alkali metal sulfide to produce an alkali metal sulfide substantially free of hydrolyzed alkali metal by-products; thereby providing a process for producing a water-reactive alkali metal sulfide material. The present invention provides a low-cost and scalable manufacturing process for high-purity alkali metal sulfides, or materials containing alkali metal sulfides and alkali metal salts.

[0012] In the method of the present invention, examples of alkali metal salts include, but are not limited to, LiCl, and examples of sulfide precursor compounds include, but are not limited to, K2S and Na2S. In a typical method for producing Li2S, LiCl and Na2S are used in combination with NaCl as a by-product, but any sulfide of a monovalent cation soluble in a polar solvent can be used instead of Na2S, as long as the corresponding by-product chloride has low solubility. The alkali metal salts and sulfide compounds may generally be in powder form for easier dissolution. The particle size can be reduced to one suitable for the method using ball milling or other processes. The alkali metal salts and sulfide compounds are substantially anhydrous, with a water content of 0% to 5% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass, and most preferably less than 200 ppm, which does not adversely affect the present invention. Similarly, the polar organic solvent is preferably substantially anhydrous, with a water content in the range of 0% to 5% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass, and most preferably less than 200 ppm. The degree of hydration can affect hydrolysis, complicating precipitation and separation processes and potentially reducing the purity of the resulting alkali metal sulfide. For example, the desirable alkali metal sulfide Li2S is highly water-soluble and hydrolyzes to LiOH and H2S. This complicates the purification and extraction of by-products. To reduce the hydration of precursor materials before use, heating, drying, or vacuum treatment can be used. Furthermore, treatment with inert gas and under anhydrous and / or vacuum conditions can maintain the degree of hydration throughout various process steps.

[0013] The alkali metal salt and sulfide compound powders may be added individually or together to a polar solvent. Alternatively, the powders may be mixed before being added to the polar solvent, or each / each may be dissolved individually in the solution before adding the other material to the combined solution. The exact form is not limited to powder and may be provided as flakes, granules, or a coarser form. Typical solvents include, but are not limited to, alcohols such as ethanol, 1-propanol, and 1-butanol. The solvent is not particularly limited as long as it provides a sufficient solubility difference between the highly solubility alkali metal sulfide and the less solubility by-products and does not involve harmful side reactions with the alkali metal salt, sulfide compound, alkali metal sulfide, and / or by-products. For example, the solubility ratio of Li2S to NaCl in ethanol is at least 97:3, the solubility ratio of Li2S to NaCl in 1-propanol is at least 99:1, and the solubility ratio of Li2S to NaCl in 1-butanol is at least 99.9:0.1. In the specific examples below, neither Na2S nor Li2S reacts with polar solvents to a considerable extent, and the byproduct NaCl has substantially lower solubility in polar solvents compared to alkali metal sulfides.

[0014] In one embodiment, if the products of the above reaction (alkali metal sulfide and by-products) have substantially similar solubility in polar solvents, the desired alkali metal sulfide product is difficult to purify. In another embodiment, if the processing temperature is too high, more undesirable side reactions may occur between the precursor and the solvent used. In yet another embodiment, if the processing temperature is too low, the solubility of the precursor and alkali metal sulfide may be too low to produce the desired yield.

[0015] The ratios and amounts of various precursor materials and polar solvents are not particularly limited, as long as the combination allows for the synthesis of the desired alkali metal sulfide. The ratios and amounts may vary depending on the specific synthesis conditions. For example, the ratio of solvent volume to individual precursor amounts may need to be adjusted to reduce side reactions or to control the desired purity of the resulting alkali metal sulfide. The amount of solvent used in the synthesis is not limited, as long as the amount supports the synthesis of the desired alkali metal sulfide. Furthermore, multiple solvents may be mixed with the above-mentioned compounds. For example, non-polar modifiers, such as heptane, may be present in the alcohol, as long as they do not interfere with the process by affecting solubility. Additional materials, such as co-solvents or flocculants, may be added during this process.

[0016] In another embodiment, to further increase the purity of the desired alkali metal sulfide, a sulfur source in the form of H2S or solid elemental sulfur may be introduced at any point in the process. The sulfur source can be partially or completely dissolved in a polar or nonpolar solvent before the addition of the alkali metal salt or sulfide precursor material. The sulfur source can be added to a solution containing the alkali metal salt, a solution containing the sulfide material, or both. When elemental sulfur is used and added to a solution containing the sulfide material, polysulfides, such as Na2S, may be added. X These can be formed, where X is greater than 1 and less than or equal to 10. Polysulfides can have higher solubility than their non-polysulfide versions (Na2S5 vs. Na2S). As solubility increases, less polar solvent can be used to reach the desired state of dissolution compared to using its non-polysulfide counterpart. If elemental sulfur is present during the metathesis reaction, the elemental sulfur can be dissolved in the newly formed sulfide material, e.g., Li2S X , or LiHS X(However, not limited to these), polysulfides may be formed. The polysulfides formed at this stage have higher solubility than their sulfide counterparts (Li2S8 vs. Li2S), which can lead to greater solubility separation between the desired metal sulfide and the newly formed metal salt. By increasing the solubility difference between the newly formed alkali metal sulfide and the undesirable product, the amount of polar solvent and nonpolar poor solvent required to produce the desired result can be reduced.

[0017] Since by-products can spontaneously precipitate from the solution at room temperature around 25°C, a supernatant containing highly soluble alkali metal sulfides and precipitates of less soluble by-products can be formed. Temperature adjustment, particularly cooling, can be used to alter the precipitation rate or to promote further precipitation of the less soluble by-products. Stirring or other mixing methods can be used to homogenize the solution, and the mixing time is not particularly limited, as long as it allows for proper homogenization and reaction of the alkali metal sulfides and precursors that produce the by-products. The mixing temperature is not particularly limited, as long as it allows for proper mixing and is neither too high nor too low to suppress the solubility of the alkali metal sulfides. For example, proper mixing can be achieved at temperatures of 50–120°C, for example, using a magnetic stirrer or shaft mixer. This can be carried out as a batch process or a continuous process, accelerated by a high reaction rate. Furthermore, further precipitation of the less soluble by-products can be promoted by adding a desired amount of a poor solvent, such as heptane or other aprotic chain hydrocarbons, to the solution. The poor solvent used should preferably be substantially miscible, ranging from 7:1 v / v nonpolar / alcohol to 1:2 v / v nonpolar / alcohol, preferably at least 3:1 v / v nonpolar / alcohol, without affecting the solubility of the alkali metal sulfide. Alternatively, the solubility of by-products, such as NaCl, can be further reduced by adding an additional amount of an ionic compound, such as LiCl, to the polar solvent solution, thereby replacing the need for a poor solvent. The total amount of LiCl or other alkali metal salt precursor can be 150% to 85% of the stoichiometric value, so as to improve the purity of the product and / or so that it contains a certain amount of alkali metal salt together with the final alkali metal sulfide. For example, a material product obtained by combining well-mixed Li2S and LiCl is useful as a precursor for producing sulfide solid electrolytes containing Li, S, and Cl.

[0018] To separate low-solubility by-products from the mixture and isolate the supernatant containing highly soluble alkali metal sulfide, separation methods such as centrifugation, filtration, or gravity sedimentation can be used separately or in combination. In some embodiments, filtration can be performed after the initial metathesis, and then the resulting solution / suspension can be treated by further filtration with a large amount of poor solvent. Additionally, separation such as filtration can be performed on the cooled solution.

[0019] Separation of the polar solvent from the supernatant to isolate an alkali metal sulfide substantially free of hydrolyzed alkali metal by-products can be achieved by evaporation of the polar solvent, recrystallization, and / or heating under vacuum. Note that the material may appear dry at this stage, but may contain solvents constituting up to 75% of the total mass. It may be beneficial to utilize a solvent with a low heat of vaporization that uses less energy for removal. Additionally, the solvent can be recycled and reused.

[0020] After isolation of the target alkali metal sulfide, residual bound solvents can be removed by heating at a predetermined time and temperature, for example, in an inert atmosphere such as argon or nitrogen or under vacuum before storage or use. The temperature range is not limited and can be, for example, in the range of 25°C to 900°C, more preferably 200°C to 700°C, and most preferably 350°C to 500°C.

[0021] In another embodiment, the introduction of the sulfur source may be carried out at any point during the drying or high-temperature treatment of the target alkali metal sulfide. Examples of such introduction include, but are not limited to, evaporating the solvent at high temperature under vacuum and introducing elemental sulfur into the newly dried alkali metal sulfide material by mixing, blending, or grinding. The amount of sulfur added can be 100% by mass or less of the alkali metal sulfide, more preferably 50% or less of the alkali metal sulfide, more preferably 7% by mass or less of the alkali metal sulfide, and most preferably 5% by mass or less of the alkali metal sulfide. Next, the composite containing sulfur and the alkali metal sulfide can be heated to the desired temperature at which sulfur melts or sublimes, and this heating helps to remove the solvent and convert any oxygen-containing compounds to metal sulfides.

[0022] In the present disclosure, the term "substantially" means a state close to 100% (including 100%) of a particular parameter. For example, being close to 100% can range from approximately 80% to 100%, approximately 90% to 100%, or approximately 95% to 100%.

[0023] Generally, the process of the present invention enables the low-cost synthesis of metal sulfides by dissolving an alkali metal sulfide and a metal salt in an aliphatic alcohol and / or a similar solvent in which "double ion exchange" occurs. The final result is the synthesis of the desired metal sulfide and one or more by-products, and these by-products can be filtered off by appropriately selecting the solvent or by adding a poor solvent, such as a non-polar hydrocarbon, and then filtering off the undesired products. Next, the solvent is removed, leaving the metal sulfide with the desired purity as the product. The general reaction can be defined by the following formula:

[0024]

Chemical formula

[0025] Specifically, the formation of Li2S and the case where a poor solvent is present:

[0026] [ka]

[0027] Use ethanol (EtOH):

[0028] [ka]

[0029] Use 1-propanol (PrOH) or a (linear) alcohol with a longer carbon chain than ethanol:

[0030] [ka] [Examples]

[0031] The present disclosure is described below with reference to examples. The examples are intended to illustrate the work of the disclosure and are not intended to limit the scope of the present disclosure. Unless otherwise noted, all scientific and technical terms used herein have the same meaning as those widely understood by those skilled in the art to which the present disclosure belongs. Similar or equivalent methods and materials may be used in carrying out the disclosed methods and compositions, but typical methods, apparatus and materials are described herein.

[0032] Example 1 1.0 g of anhydrous Na2S was dissolved in 16 g of anhydrous ethanol containing less than 50 ppm of water. Separately, approximately 1.09 g of anhydrous LiCl (stoichiometric amount) was dissolved in 6 g of anhydrous ethanol containing less than 50 ppm of water. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was cooled to -25°C, and then centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove 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 approximately 15% binding solvent. The product was further heat-treated under argon at 400°C for 1 hour. This step helped to remove the residual solvent and sinter the Li2S to a microscale. The purity of the resulting alkali metal sulfide was approximately 87%, with lithium oxychloride (Li3ClO) being the main impurity, exhibiting the highest intensity XRD peak at approximately 32.3°. Sodium chloride by-products were present at a solubility of approximately 1.5% below room temperature due to cooling.

[0033] Example 2 1.0 g of anhydrous Na2S was dissolved in 16 g of anhydrous ethanol containing less than 50 ppm of water. Separately, approximately 1.06 g of anhydrous LiCl (2.5% stoichiometric amount) was dissolved in 6 g of anhydrous ethanol containing less than 50 ppm of water. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was cooled to -25°C, and then centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove 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 approximately 15% of the binding solvent. The product was further heat-treated under argon at 400°C for 1 hour. This process helped remove residual solvent and sinter Li2S down to the microscale. The purity of the resulting alkali metal sulfide was approximately 89%, with the main impurity being lithium oxide (Li2O), which had the highest intensity XRD peak at approximately 33.5°. Sodium chloride byproducts were present at approximately 2.1%. Furthermore, the amount of lithium oxychloride was reduced from 7.7% to 1.5% compared to the stoichiometric synthesis.

[0034] Example 3 1.0 g of anhydrous Na2S was dissolved in 16 g of anhydrous ethanol, and separately, approximately 1.1 g of anhydrous LiCl was dissolved in 6 g of anhydrous ethanol. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). Despite the low solubility of NaCl in ethanol, approximately 10% by mass of the product at this stage was NaCl due to supersaturation. 60 g of heptane was added as a poor solvent to the recovered supernatant, yielding a dense suspension. This suspension was centrifuged at 2000 rpm for 30 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, the solvent was removed from the supernatant using a rotary evaporator at 200°C under vacuum. After removing most of the solvent, the product was further heat-treated at 400°C under argon for 1 hour. This process helped to thoroughly dry the product and sinter the Li2S down to the microscale. The resulting alkali metal sulfide had a purity of over 95%.

[0035] Example 4 1.0 g of anhydrous Na2S was dissolved in 14 g of anhydrous 1-propanol, and separately, approximately 1.1 g of anhydrous LiCl was dissolved in 10 g of anhydrous 1-propanol. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was cooled to -25°C, and then centrifuged at 4000 rpm for 40 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, 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 approximately 30% binding solvent. After removing most of the solvent, the product was further heat-treated under argon at 400°C for 1 hour. This step helped to thoroughly dry the product and sinter the Li2S to a microscale. The purity of the obtained alkali metal sulfide was approximately 81%. The main impurities were lithium chloride, with peaks at 30.1° and 34.8°, and lithium oxychloride (Li3ClO), with the highest intensity XRD peak at approximately 32.3°. Sodium chloride by-products were present at approximately 0.1%.

[0036] Example 5 1.0 g of anhydrous Na2S was dissolved in 14 g of anhydrous 1-propanol, and separately, approximately 1.06 g of anhydrous LiCl (2.5% stoichiometric amount) was dissolved in 10 g of anhydrous 1-propanol. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was cooled to -25°C, and then the supernatant, which was mostly Li2S in alcohol, was separated by centrifugation at 4000 rpm for 40 minutes, and the insoluble NaCl byproduct was removed. 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 approximately 30% binding solvent. After most of the solvent was removed, the product was further heat-treated under argon at 400°C for 1 hour. This process helped to thoroughly dry the residual solvent and sinter the Li2S down to the microscale. The purity of the resulting alkali metal sulfide was approximately 90%, with the main impurities being lithium oxide, which had the highest intensity XRD peak at approximately 33.5°, and lithium carbonate (LiCO3). Sodium chloride byproducts were present at approximately 0.3%. Furthermore, the amount of lithium oxychloride was significantly reduced compared to stoichiometric synthesis.

[0037] Example 6 1.0 g of anhydrous Na2S was dissolved in 19 g of anhydrous 1-butanol, and separately, approximately 1.1 g of anhydrous LiCl was dissolved in 13 g of anhydrous 1-butanol. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was centrifuged at 4000 rpm for 50 minutes to separate the supernatant, which at this point consisted mostly of Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, the alcohol was removed from the supernatant using a rotary evaporator at 30°C. After removing most of the solvent, the product was further heat-treated under argon at 400°C for 1 hour. This step helped to thoroughly dry the product and sinter the Li2S to a microscale. The purity of the resulting alkali metal sulfide was approximately 90%. The main impurities were lithium oxide, which had the highest intensity XRD peak at 33.5°, and lithium carbonate (Li2CO3). Sodium chloride by-products were present at a concentration of approximately 0.3%.

[0038] Example 7 1.0 g of anhydrous Na2S was dissolved in 12 g of a mixture of 95.6% ethanol and 4.4% water. Dissolution was incomplete because some Na2S formed an insoluble hydrate in the alcohol, as disclosed in U.S. Patent No. 2,838,374. Separately, approximately 1.09 g of anhydrous LiCl was dissolved in 6 g of 95.6% ethanol. The LiCl solution was then weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, the majority 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 approximately 15% binding solvent. The product was further heat-treated under argon at 400°C for 1 hour. This step helped remove residual solvent and sinter the Li2S down to the microscale. The purity of the resulting alkali metal sulfide was approximately 68%, with the main impurities being 14% lithium hydroxide, 8% sodium chloride, and 9% lithium oxide.

[0039] Example 8 1.0 g of anhydrous Na2S was dissolved in 16 g of anhydrous ethanol, and approximately 1.1 g of anhydrous LiCl was added to the Na2S ethanol solution while continuously stirring the solution. Precipitation occurred immediately at room temperature (25°C). The mixture was cooled to -25°C, and then centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, the alcohol was removed from the supernatant using a rotary evaporator at 200°C under vacuum. Once the product was dry, the mixture was further heat-treated under argon at 400°C for 1 hour. The purity of the resulting alkali metal sulfide was approximately 90%. The main impurity was 5.7% lithium oxychloride Li3ClO, with the highest intensity XRD peak at approximately 32.3°. Sodium chloride by-product was present at approximately 1.3%.

[0040] Example 9 1.0 g of anhydrous Na2S was dissolved in 10 g of anhydrous ethanol containing less than 50 ppm of water. Separately, approximately 1.06 g of anhydrous LiCl (2.5% stoichiometric amount) was dissolved in 6 g of anhydrous ethanol containing less than 50 ppm of water. Next, the LiCl solution was weighed into the continuously stirred Na2S solution. Precipitation occurred immediately at around room temperature (25°C). The mixture was cooled to -25°C, and then centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S in alcohol, and remove the insoluble NaCl by-product. At this point, under vacuum and at 200°C, the majority of the alcohol was removed from the supernatant using a rotary evaporator. At this stage, the material appeared dry but contained approximately 15% of the binding solvent. The product was blended with approximately 0.03 g of elemental sulfur (5% by mass) using a mortar and pestle, and then further heat-treated under argon at 400°C for 1 hour. This step helped to remove residual solvent and reduce residual impurities to sulfides. The purity of the resulting alkali metal sulfide was approximately 94%, with the main impurity being lithium carbonate, which had the highest intensity XRD peak at approximately 31.8°. Sodium chloride by-products were present at approximately 1.1%. Lithium oxychloride and lithium oxide were completely eliminated.

[0041] Example 10 1.0 g of anhydrous Na2S mixed with 0.059 g of elemental sulfur (10% by mass of the expected Li2S yield) was dissolved in 12 g of anhydrous ethanol. The solution was yellow, indicating the presence of polysulfides. Separately, approximately 1.2 g of anhydrous LiCl (10% excess relative to the stoichiometric amount) was dissolved in 6 g of anhydrous ethanol. Next, the LiCl solution was continuously stirred with Na2S. xThe solution was measured and added. Precipitation occurred immediately at around room temperature (25°C). Next, the mixture was centrifuged at 4000 rpm for 10 minutes to separate the supernatant, which at this point was mostly Li2S with excess LiCl in the alcohol, and to remove the insoluble NaCl by-product. At this point, the alcohol was removed from the supernatant using a rotary evaporator at 200°C under vacuum. Once most of the solvent had been removed and the product was dry, the mixture was further heated at 400°C under argon for 1 hour. The polysulfides underwent disproportionation, becoming Li2S and free sulfur, and the free sulfur reduced the present impurities, resulting in more sulfides. The purity of the resulting alkali metal sulfide was 86%. The main impurity was excess lithium chloride precursor, which was present at approximately 10.9%, with the highest intensity XRD peaks at approximately 30.1° and 34.9°.

[0042] The features described above, as well as those described in the claims below, can be combined in various ways without departing from the scope of the claims. The embodiments described above illustrate several possible non-limiting combinations. Therefore, it should be noted that the contents included in the above description or shown in the accompanying drawings should be interpreted as illustrative, not limiting. The embodiments described above should be considered as examples of the present invention, not as limiting the scope of various inventions. In addition to the embodiments described above, a detailed description and a detailed description of the accompanying drawings will make it clear that there are other embodiments of the present invention. Accordingly, many combinations, substitutions, changes, and modifications of the embodiments described above of the invention, even if not expressly shown in this disclosure, are included in the scope of the present invention. Some embodiments of the present invention are shown below. [Embodiment 1] A method for producing water-reactive alkali metal sulfide compounds, Dissolving a substantially anhydrous alkali metal salt precursor and a substantially anhydrous sulfide precursor compound in one or more substantially anhydrous polar solvents, wherein the polar solvent provides a solubility difference between the highly solubility alkali metal sulfide and the less solubility by-products; To form a mixture comprising the supernatant of the highly soluble alkali metal sulfide dissolved in the polar solvent and the precipitate of the low-solubility by-product; To separate the precipitate of the low-solubility by-product from the supernatant; Evaporating the polar solvent from the supernatant; and Final heat treatment for isolating the alkali metal sulfide; Methods that include... [Embodiment 2] The method according to Embodiment 1, further comprising adding a sulfur source at any point during the process to increase the purity of the final alkali metal sulfide product. [Embodiment 3] The sulfur source is elemental sulfur and H 2 The method according to Embodiment 2, comprising one or more of S. [Embodiment 4] The method according to Embodiment 2, wherein the sulfur source is added to one or more of the following: the solution of the sulfide precursor, the solution of the alkali metal salt precursor, the mixture of the combined sulfide and alkali metal salt, and the isolated alkali metal sulfide before heat treatment. [Embodiment 5] The isolated alkali metal sulfide material is further divided into Li 3 The OCl phase contains the Li 3 The method according to Embodiment 2, wherein the OCl phase may subsequently be removed after the sulfur source addition and subsequent heat treatment steps. [Embodiment 6] Furthermore, the method according to Embodiment 1, comprising introducing a poor solvent compound into the supernatant of the highly soluble alkali metal sulfide and the polar solvent immediately after the precipitation of the low-solubility by-product. [Embodiment 7] The method according to Embodiment 1, further comprising separating the low-solubility by-product from the supernatant by at least one of centrifugation, filtration, gravity sedimentation, and cooling. [Embodiment 8] The method according to Embodiment 1, wherein separating the polar solvent from the supernatant further comprises at least one of evaporating the polar solvent, recrystallizing it, and heating it under vacuum. [Embodiment 9] The method according to Embodiment 1, further comprising adjusting the relative amounts of the alkali metal salt precursor and the sulfide precursor compound added to the solution to adjust the purity of the resulting alkali metal sulfide. [Embodiment 10] The method according to Embodiment 9, wherein the obtained alkali metal sulfide material further comprises an alkali metal salt precursor. [Embodiment 11] The method according to Embodiment 6, wherein the poor solvent is selected from heptane and one or more other nonpolar solvents that are substantially miscible in the polar solvent, and the poor solvent increases the solubility difference between the alkali metal sulfide and the by-product. [Embodiment 12] The method according to Embodiment 1, wherein the substantially anhydrous polar solvent is at least one alcohol selected from the group consisting of ethanol, 1-propanol, 1-butanol, ethanol modifiers, and mixtures thereof. [Embodiment 13] The method according to Embodiment 1, wherein the alkali metal salt precursor is LiCl. [Embodiment 14] The method according to Embodiment 1, wherein the alkali metal salt precursor and the sulfide precursor compound are dissolved independently in the polar solvent before the formation of a combined mixture. [Embodiment 15] The method according to Embodiment 1, wherein one of the alkali metal salt precursor and the sulfide precursor compound is dissolved in the polar solvent, and the other is added to the solution in solid form. [Embodiment 16] The method according to Embodiment 1, wherein the ratio of the solubility of the alkali metal sulfide to the solubility of the by-product in the polar solvent is at least 90:10. [Embodiment 17] The method according to Embodiment 1, wherein the ratio of the solubility of the alkali metal sulfide to the solubility of the by-product in the polar solvent is at least 97:3. [Embodiment 18] The method according to Embodiment 1, wherein the ratio of the solubility of the alkali metal sulfide to the solubility of the by-product in the polar solvent is at least 99:1. [Embodiment 19] The method according to Embodiment 1, wherein the ratio of the solubility of the alkali metal sulfide to the solubility of the by-product in the polar solvent is at least 99.9:0.1. [Embodiment 20] The aforementioned sulfide precursor compound is K 2 S, Na 2 S and (NH 4 ) 2 The method according to Embodiment 1, selected from the group consisting of S. [Embodiment 21] The alkali metal sulfide is Li 2 The method according to Embodiment 1, wherein S. [Embodiment 22] The method according to Embodiment 1, further comprising drying the obtained alkali metal sulfide. [Embodiment 23] A solid electrolyte comprising the water-reactive alkali metal sulfide produced by the method described in Embodiment 1. [Embodiment 24] A solid electrolyte comprising a material containing alkali metal sulfides and alkali metal salts, manufactured by the method described in Embodiment 10. [Embodiment 25] The alkali metal sulfide is Li 2 The method according to embodiment 23, wherein S. [Embodiment 26] The alkali metal sulfide is Li 2 The solid electrolyte according to Embodiment 24, wherein the alkali metal salt is S and one or more of LiCl and LiBr. [Embodiment 27] A solid battery comprising the water-reactive alkali metal sulfide manufactured by the method described in Embodiment 1. [Embodiment 28] The alkali metal sulfide is Li 2 A solid battery according to embodiment 27, wherein S is the solid battery. [Embodiment 29] A vehicle powered by a battery containing the water-reactive alkali metal sulfide manufactured by the method described in Embodiment 1. [Embodiment 30] The alkali metal sulfide is Li 2 The vehicle described in embodiment 29, which is S. [Embodiment 31] A method for producing lithium sulfide, Essentially anhydrous LiCl and Na 2 S and K 2 A substantially anhydrous sulfide compound selected from S is dissolved in a solvent selected from ethanol, 1-propanol, and 1-butanol. The aforementioned solution is subjected to a precipitation treatment to obtain highly soluble Li 2 Formation of a supernatant of alkali metal sulfide and solvent, and a precipitate of low-solubility chloride by-products; Separating the low-solubility by-product from the supernatant; and The solvent is evaporated from the supernatant, Li 2 To isolate S; Methods that include... [Embodiment 32] Furthermore, the method according to Embodiment 31, further comprising adding a sulfur source. [Embodiment 33] The sulfur source comprises elemental sulfur and H 2 The method according to Embodiment 32, further comprising one or more of S. [Embodiment 34] Furthermore, immediately after the precipitation of the low-solubility by-product, the poor solvent compound is introduced into the supernatant of the high-solubility alkali metal sulfide and the polar solvent. The method according to Embodiment 31, wherein the poor solvent is selected from heptane and one or more other nonpolar solvents that are substantially miscible in the polar solvent, and the poor solvent increases the solubility difference between the alkali metal sulfide and the by-product.

Claims

1. Li ２ A method for manufacturing S, Dissolving a lithium halide having a water content in the range of 0 to 5% by mass and a sulfide precursor compound having a water content in the range of 0 to 5% by mass individually or together in one or more substantially anhydrous polar solvents having a water content in the range of 0 to 5% by mass to form a solution of the lithium halide and a solution of the sulfide precursor compound, and then combining the solution of the lithium halide and the solution of the sulfide precursor compound, or forming a solution of the lithium halide and the sulfide precursor compound; From the combination of the lithium halide solution and the sulfide precursor compound solution, or from the lithium halide and the sulfide precursor compound solution, Li dissolved in the polar solvent ２ To form a mixture containing a supernatant containing sulfur and a precipitate of chloride by-products; Separating the supernatant from the chloride by-product precipitate; and The polar solvent is evaporated from the supernatant to obtain Li ２ To isolate S; Includes, The sulfide precursor compound is K ２ S and Na ２ Selected from S; A method in which one or more polar solvents are selected from alcohols.

2. Furthermore, the final Li ２ The method according to claim 1, further comprising adding a sulfur source at any point during the process to increase the purity of the S product.

3. The sulfur source is elemental sulfur and H ２ The method according to claim 2, comprising one or more of S.

4. The sulfur source is a solution of the sulfide precursor compound, a solution of the lithium halide, a combination of the solution of the sulfide precursor compound and the solution of the lithium halide, and isolated Li before heat treatment. ２ The method according to claim 2, wherein one or more of S are added.

5. The isolated Li ２ S further contains a Li ３ OCl phase, and the Li ３ OCl phase may subsequently be removed after the sulfur source addition and subsequent heat treatment step, the method according to claim 2.

6. Furthermore, immediately after the precipitation of the chloride by-product, the Li ２ The method according to claim 1, comprising introducing a poor solvent into the supernatant of S and the polar solvent.

7. The method according to claim 1, wherein separating the supernatant from the chloride by-product further comprises at least one of centrifugation, filtration, gravity sedimentation, and cooling.

8. The method according to claim 1, wherein separating the polar solvent from the supernatant further comprises at least one of evaporating the polar solvent, recrystallizing it, and heating it under vacuum.

9. Furthermore, by adjusting the relative amounts of the lithium halide and the sulfide precursor compound, the resulting Li ２ The method according to claim 1, comprising adjusting the purity of S.

10. The obtained Li ２ The method according to claim 9, wherein S further comprises the lithium halide.

11. The poor solvent is selected from heptane and one or more other nonpolar solvents that are miscible in the polar solvent, and the poor solvent is Li ２ The method according to claim 6, which increases the solubility difference between S and the chloride by-product.

12. The method according to claim 1, wherein the polar solvent is at least one alcohol selected from the group consisting of ethanol, 1-propanol, 1-butanol, an ethanol denaturant, and mixtures thereof.

13. The method according to claim 1, wherein the lithium halide and the sulfide precursor compound are dissolved independently in the polar solvent before the formation of a combined mixture.

14. The method according to claim 1, wherein one of the lithium halide and the sulfide precursor compound is dissolved in the polar solvent, and the other is added to the polar solvent in solid form.

15. The Li in the polar solvent ２ The method according to claim 1, wherein the ratio of the solubility of S to the solubility of the chloride by-product is at least 90:

10.

16. The Li in the polar solvent ２ The method according to claim 1, wherein the ratio of the solubility of S to the solubility of the chloride by-product is at least 97:

3.

17. The Li in the polar solvent ２ The method according to claim 1, wherein the ratio of the solubility of S to the solubility of the chloride by-product is at least 99:

1.

18. The Li in the polar solvent ２ The method according to claim 1, wherein the ratio of the solubility of S to the solubility of the chloride by-product is at least 99.9:0.

1.

19. Furthermore, the obtained Li ２ The method according to claim 1, comprising drying S.

20. The solid electrolyte according to claim 1, wherein the lithium halide is one or more of LiCl and LiBr.

21. A method for producing lithium sulfide, LiCl having a water content in the range of 0 to 5% by mass, and Na ２ S and K ２ Dissolving a sulfide compound having a water content in the range of 0 to 5% by mass, selected from S, in a polar solvent selected from ethanol, 1-propanol, and 1-butanol to form a solution; The aforementioned solution is subjected to a precipitation treatment, Li ２ Formation of a supernatant of S and solvent, and a precipitate of chloride by-products; Separating the supernatant from the chloride by-product; and The solvent is evaporated from the supernatant, Li ２ To isolate S; Methods that include...

22. The method according to claim 21, further comprising adding a sulfur source.

23. The sulfur source comprises elemental sulfur and H ２ The method according to claim 22, further comprising one or more of S.

24. Furthermore, immediately after the precipitation of the chloride by-product, the Li ２ This includes introducing a nonpolar hydrocarbon into S and the supernatant of the polar solvent, The method according to claim 21, wherein the nonpolar hydrocarbon is selected from heptane and one or more other nonpolar hydrocarbons that are miscible in the polar solvent, and the nonpolar hydrocarbon increases the solubility difference between the Li₂S and the chloride byproduct.

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