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JP-7856569-B2 - Method for producing water-reactive sulfide materials

JP7856569B2JP 7856569 B2JP7856569 B2JP 7856569B2JP-7856569-B2

Inventors

  • イルヤ ライゼンカー
  • ショーン カルバー

Assignees

  • ソリッド パワー オペレーティング， インコーポレイティド

Dates

Publication Date
20260511
Application Date
20210217
Priority Date
20200217

Claims (20)

  1. A method for producing Li2S , 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; Forming a mixture from a combination of the lithium halide solution and the sulfide precursor compound solution, or from the lithium halide and the sulfide precursor compound solution, the mixture containing a supernatant containing Li₂S dissolved in the polar solvent and a precipitate of chloride by-products; Separating the supernatant from the chloride by-product precipitate; and evaporating the polar solvent from the supernatant to isolate Li₂S ; Includes, The sulfide precursor compound is selected from K₂S and Na₂S ; A method in which one or more polar solvents are selected from alcohols.
  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 final Li₂S product.
  3. The method according to claim 2, wherein the sulfur source comprises one or more of elemental sulfur and H₂S .
  4. The method according to claim 2, wherein the sulfur source is added to one or more of the following: 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 Li₂S before heat treatment.
  5. The method according to claim 2, wherein the isolated Li2S further comprises a Li3OCL phase, the Li3OCL phase being subsequently removed after the sulfur source addition and subsequent heat treatment steps.
  6. The method according to claim 1, further comprising introducing a poor solvent into the supernatant of the Li₂S and the polar solvent immediately after the precipitation of the chloride by-product.
  7. The method according to claim 1, wherein the separation of the supernatant and 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. The method according to claim 1, further comprising adjusting the relative amounts of the lithium halide and the sulfide precursor compound to adjust the purity of the resulting Li₂S .
  10. The method according to claim 9, wherein the obtained Li₂S further comprises the lithium halide.
  11. The method according to claim 6, wherein the poor solvent is selected from one or more of heptane and other nonpolar solvents miscible in the polar solvent, and the poor solvent increases the solubility difference between the Li₂S and the chloride byproduct.
  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 independently dissolved 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 method according to claim 1, wherein the ratio of the solubility of Li₂S to the solubility of the chloride by-product in the polar solvent is at least 90:10.
  16. The method according to claim 1, wherein the ratio of the solubility of Li₂S to the solubility of the chloride by-product in the polar solvent is at least 97:3.
  17. The method according to claim 1, wherein the ratio of the solubility of Li₂S to the solubility of the chloride by-product in the polar solvent is at least 99:1.
  18. The method according to claim 1, wherein the ratio of the solubility of Li₂S to the solubility of the chloride by-product in the polar solvent is at least 99.9:0.1.
  19. The method according to claim 1, further comprising drying the obtained Li2S .
  20. The solid electrolyte according to claim 1, wherein the lithium halide is one or more of LiCl and LiBr.

Description

Related Applications This application claims priority to U.S. Provisional Patent Application No. 62/977,505, filed on 17 February 2020, and U.S. Provisional Patent Application No. 63/140,624, filed on 22 January 2021. The entire contents of these applications are incorporated herein by reference, respectively. The various embodiments described in this disclosure relate to the field of producing alkali metal sulfide compounds that can be used in solid primary and secondary electrochemical cells, electrodes and electrode materials, electrolytes and electrolyte compositions. Figure 1 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Examples 1, 2, and 3. Figure 2 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Examples 4 and 5. Figure 3 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Example 6.Figure 4 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Example 7.Figure 5 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Example 8.Figure 6 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Example 9.Figure 7 shows the X-ray diffraction pattern of lithium sulfide ( Li₂S ) synthesized in Example 10. The following description provides specific details to ensure that various embodiments of the present invention are 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 presented 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. 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. 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. A 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. 3,642,436) teaches the reaction of alkali metals with hydrogen sulfide or sulfur vapor, but this method requires relatively expensive lithium metal and handling large quantities of hydrogen sulfide, a highly toxic and flammable gas. Mehta (U.S. Patent No. 6,555,078) teaches a method of reacting a lithium salt with the sodium salt of the desired anion in an aqueous or semi-aqueous solution; however, this process is unsuitable 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 method using sulfur vapor to reduce alkali metal carbonates or hydroxides. 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 method of reacting a lithium metal base with a hydrogen sulfide in an organic solvent; however, this method uses expensive lithium organic compounds as precursors. The present invention provides a process for producing water-reactive alkali metal sulfide materials, 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 s