Search

CN-122025628-A - Lithium sulfide, preparation method thereof and solid-state battery

CN122025628ACN 122025628 ACN122025628 ACN 122025628ACN-122025628-A

Abstract

The application provides lithium sulfide, a preparation method thereof and a solid-state battery, and belongs to the technical field of batteries, wherein the preparation method of the lithium sulfide comprises the steps of carrying out hydrosulfide reaction on hydrous hydrosulfide and lithium salt dissolved in a first solvent under the protection of inert gas to obtain a first lithium hydrosulfide suspension, and carrying out solid-liquid separation to obtain a first lithium hydrosulfide solution, wherein the first solvent comprises an aprotic polar organic solvent; the first lithium hydrosulfide solution is decompressed and dehydrated to obtain a second lithium hydrosulfide suspension, the second lithium hydrosulfide suspension is obtained through solid-liquid separation, the water content in the second lithium hydrosulfide suspension is 0.05% -2%, the second lithium hydrosulfide solution is desulfurized to obtain a lithium sulfide suspension, and lithium sulfide is obtained through solid-liquid separation. The application selects low-cost hydrous hydrosulfide as a raw material, adds a decompression water removal process to remove impurities, and then carries out desulfurization to obtain high-purity lithium sulfide.

Inventors

  • Xiong Hougao
  • LUO WEN
  • WANG DONGWEI
  • LIU QIANG
  • Tu Huazhen
  • SHI QIHUA
  • WANG JINTAO
  • LV ZHENGZHONG

Assignees

  • 湖北金泉新材料有限公司

Dates

Publication Date
20260512
Application Date
20251226

Claims (11)

  1. 1. A method for preparing lithium sulfide, comprising: Carrying out hydrosulfide reaction on aqueous hydrosulfide and lithium salt dissolved in a first solvent under the protection of inert gas to obtain a first lithium hydrosulfide suspension, and carrying out solid-liquid separation to obtain a first lithium hydrosulfide solution, wherein the first solvent comprises an aprotic polar organic solvent; decompressing and dewatering the first lithium hydrosulfide solution to obtain a second lithium hydrosulfide suspension, and carrying out solid-liquid separation to obtain a second lithium hydrosulfide solution, wherein the water content in the second lithium hydrosulfide suspension is 0.05% -2%; And desulfurizing the second lithium hydrosulfide solution to obtain a lithium sulfide suspension, and carrying out solid-liquid separation to obtain lithium sulfide.
  2. 2. The method of claim 1, wherein the second lithium bisulfide suspension has a water content of 0.05% -1%.
  3. 3. The method for producing lithium sulfide according to claim 1, wherein the pressure of the reduced-pressure water removal is-0.04 MPa to-0.10 MPa, and/or, The temperature of the decompression and water removal is 80-140 ℃.
  4. 4. A method for producing lithium sulfide according to any one of claims 1 to 3, wherein the desulfurization is performed under reduced pressure at a temperature of 110 to 135 ℃ and/or, The time of the decompression and desulfurization is 1 h-10 h, and/or, The water content of the lithium sulphide suspension is <0.5%.
  5. 5. The method for preparing lithium sulfide according to any one of claims 1 to 4, wherein the step of obtaining the first lithium hydrosulfide suspension comprises the step of performing a hydrosulfide reaction between an aqueous hydrosulfide and a lithium salt dissolved in an aprotic polar organic solvent under the protection of an inert gas: The molar ratio of the lithium salt to the aqueous hydrosulfide is 1-1.5:1, and/or, The reaction temperature of the hydrosulfide is 50-140 ℃, the reaction time is 1-10 h, and/or, The aprotic polar organic solvent comprises at least one of dimethyl sulfoxide, dimethylformamide, N-dimethylacetamide, 3-methoxy-N, N-dimethylpropionamide, N-methylpyrrolidone, N-alkylcaprolactam and N-alkylpyrrolidone, and/or, The aqueous hydrosulfide comprises at least one of aqueous potassium hydrosulfide and aqueous sodium hydrosulfide, and/or, The lithium salt comprises lithium chloride.
  6. 6. The method for preparing lithium sulfide according to any one of claims 1 to 5, wherein the desulfurizing the second lithium bisulfide solution to obtain a lithium sulfide suspension, and after solid-liquid separation, obtaining lithium sulfide comprises: and desulfurizing the second lithium bisulfide solution to obtain the lithium sulfide suspension, carrying out solid-liquid separation to obtain a first solid, and washing the first solid to obtain the lithium sulfide and the washing liquid.
  7. 7. The method for producing lithium sulfide according to claim 6, wherein the washing temperature of the washing is 80 to 120 ℃ and/or, The washing time of the washing is 15 min-300 min, and/or, The washing solvent of the washing is the aprotic polar organic solvent.
  8. 8. The method for producing lithium sulfide according to claim 6, wherein the washing liquid is used as the first solvent, and/or, The aqueous hydrosulfide and the lithium salt dissolved in the first solvent are subjected to hydrosulfide reaction under the protection of inert gas to obtain a first lithium hydrosulfide suspension, a second solid is obtained after solid-liquid separation, the washing liquid is used for washing the second solid, and/or, The second lithium hydrosulfide solution is subjected to reduced pressure desulfurization to obtain lithium sulfide suspension, and after solid-liquid separation, a recovery solution is obtained, wherein the recovery solution is used as the first solvent, and/or, And decompressing and removing water from the first lithium hydrosulfide solution to obtain a second lithium hydrosulfide suspension, and separating solid from liquid to obtain a third solid, wherein the third solid is used as the lithium salt.
  9. 9. The lithium sulfide is characterized in that the lithium sulfide is prepared by the preparation method of any one of claims 1-8, wherein the particle size of D10 of the lithium sulfide is 0.7-0.9 mu m, the particle size of D50 is 6.5-8.5 mu m, and the particle size of D100 is 19-21 mu m.
  10. 10. Lithium sulphide according to claim 9, wherein the metal-based purity of the lithium sulphide is >99.9%, and/or, The lithium sulphide has a cationic impurity content of <500ppm, and/or, The lithium sulfide has a lithium sulfite content of <0.05% and a lithium sulfate content of <0.03%.
  11. 11. A solid-state battery comprising a solid electrolyte membrane, wherein the solid electrolyte membrane comprises lithium sulfide prepared by the method for preparing lithium sulfide according to any one of claims 1 to 8 or lithium sulfide according to any one of claims 9 to 10.

Description

Lithium sulfide, preparation method thereof and solid-state battery Technical Field The application relates to the technical field of batteries, in particular to lithium sulfide, a preparation method thereof and a solid-state battery. Background In recent years, secondary batteries have been widely used and developed as a power source for portable electronic communication devices such as video cameras, cellular phones, notebook computers, and vehicles such as hybrid cars and electric cars. Lithium secondary batteries have characteristics of high operating voltage, high energy density, rapid charge and light weight, and have been widely studied, wherein safety, energy density and service life of all-solid-state batteries (all solid battery) are superior to those of liquid batteries, and are becoming research hot spots. Sulfide-based solid electrolytes are mainly prepared from lithium sulfide (Li 2 S), but lithium sulfide cannot be prepared from natural minerals and needs to be synthesized artificially. The original method for industrially producing lithium sulfide mainly comprises a carbothermic reduction method, a ball milling method, a double decomposition method, a gas-solid reaction method and the like, but the methods have the problems of difficult control of impurity content, low safety, low conversion rate, low yield and the like. In order to solve the above problems, lithium bisulfide is prepared by hydrosulfide and lithium salt through hydrosulfide reaction in the related art, and then lithium sulfide is obtained through desulfurization. However, the anhydrous starting materials used in this process are costly, while the purity of the lithium sulfide obtained is relatively low. Disclosure of Invention The application provides lithium sulfide, a preparation method thereof and a solid-state battery, and aims to solve the problems of higher cost of anhydrous raw materials and lower purity of the obtained lithium sulfide in the existing process of preparing the lithium sulfide through a hydrosulfide reaction. In a first aspect, embodiments of the present application provide a method for preparing lithium sulfide, including: carrying out hydrosulfide reaction on aqueous hydrosulfide and lithium salt dissolved in a first solvent under the protection of inert gas to obtain a first lithium hydrosulfide suspension, and carrying out solid-liquid separation to obtain a first lithium hydrosulfide solution, wherein the first solvent comprises an aprotic polar organic solvent; decompressing and dewatering the first lithium hydrosulfide solution to obtain a second lithium hydrosulfide suspension, and carrying out solid-liquid separation to obtain a second lithium hydrosulfide solution, wherein the water content in the second lithium hydrosulfide suspension is 0.05% -2%; And (3) carrying out reduced pressure desulfurization on the second lithium bisulfide solution to obtain a lithium sulfide suspension, and carrying out solid-liquid separation to obtain lithium sulfide. According to the method, firstly, a lithium bisulfide suspension is obtained through low-cost hydrosulfide and lithium salt hydrosulfide reaction, after solid-liquid separation, a first lithium bisulfide solution is obtained, secondly, on the basis of using low-cost hydrosulfide, the obtained first lithium bisulfide solution is subjected to reduced pressure water removal, along with the removal of water, impurities in the first lithium bisulfide solution are continuously separated out, the water content of a second lithium bisulfide suspension is controlled to be 0.05% -2%, so that the impurities in the first lithium bisulfide solution are greatly removed, a high-purity second lithium bisulfide solution is obtained, guarantee is provided for preparing high-purity lithium bisulfide, the reduced pressure water removal temperature is reduced while the high-efficiency water removal is carried out, the decomposition of an aprotic polar organic solvent is reduced, and then the high-purity lithium bisulfide target product is obtained through desulfurization of the second lithium bisulfide solution after the impurity removal. Optionally, the water content in the second lithium bisulfide suspension is 0.05% -1%. According to the application, the water content in the second lithium hydrosulfide suspension is further controlled, so that 99.5% -99.9% of impurities are converted into precipitates in the process of reduced pressure water removal, and the content of cationic impurities in the second lithium hydrosulfide solution is less than 200ppm. Optionally, the pressure of the reduced pressure water removal is-0.04 MPa to-0.10 MPa, and/or the temperature of the reduced pressure water removal is 80 ℃ to 140 ℃. According to the application, the pressure and the temperature of the decompression and water removal are reasonably set, and the decomposition loss of the aprotic polar organic solvent is reduced while the efficient removal of water can be ensured throug