Search

CN-121974301-A - Preparation method of lithium sulfide, solid electrolyte and solid battery

CN121974301ACN 121974301 ACN121974301 ACN 121974301ACN-121974301-A

Abstract

The application discloses a preparation method of lithium sulfide, a solid electrolyte and a solid battery, wherein the lithium sulfide is used for preparing the solid electrolyte, and the preparation method comprises the steps of uniformly mixing lithium sulfate, an organic carbon source and a high polymer in a solvent to obtain a mixed solution, wherein the mass ratio of the lithium sulfate to the organic carbon source is 1 (0.7-1), the mass ratio of the organic carbon source to the high polymer is 0.7-1 (0.1-2.5), the ratio of the sum of the residual carbon amount of the organic carbon source and the residual carbon amount of the high polymer to the mass of the lithium sulfate is 0.2-0.25 (1), spray-drying the mixed solution to obtain a precursor material, and sintering the precursor material to obtain the product lithium sulfide. The sulfide solid electrolyte prepared by the preparation method provided by the application has high purity and low carbon impurity content.

Inventors

  • YANG YONG
  • ZHAO LIPING
  • ZHANG ZHONGRU
  • CAI YAQING
  • WANG JINGJING
  • WANG WEILI

Assignees

  • 厦门固纳新能源材料股份有限公司

Dates

Publication Date
20260505
Application Date
20260204
Priority Date
20251208

Claims (10)

  1. 1. A method for preparing lithium sulfide, wherein the lithium sulfide is used for preparing a solid electrolyte, comprising the following steps: Uniformly mixing lithium sulfate, an organic carbon source and a high polymer in a solvent to obtain a mixed solution, wherein the mass ratio of the lithium sulfate to the organic carbon source is 1 (0.7-1), the mass ratio of the organic carbon source to the high polymer is 0.7-1 (0.1-2.5), and the ratio of the sum of the residual carbon amount of the organic carbon source and the residual carbon amount of the high polymer to the mass of the lithium sulfate is 0.2-0.25:1; Spray drying the mixed solution to obtain a precursor material; And sintering the precursor material to obtain the product lithium sulfide.
  2. 2. The method according to claim 1, wherein the precursor material has a particle size of 1 to 10. Mu.m, and/or the lithium sulfate has a particle size of 5 μm or less and the organic carbon source has a particle size of 1 μm or less.
  3. 3. The method according to claim 1, wherein the organic carbon source comprises at least one of glucose, sucrose, and citric acid, and/or the polymer comprises at least one of polyethylene glycol, polyvinyl alcohol, and polyoxyethylene.
  4. 4. The method of producing lithium sulfide according to claim 1, wherein the molecular weight of the high molecular polymer is 400 or less.
  5. 5. The method for producing lithium sulfide according to claim 1, wherein the solvent is water or ethanol.
  6. 6. The method of claim 1, wherein the spray-dried inlet air temperature is 100 ℃ to 200 ℃.
  7. 7. The method of preparing lithium sulfide according to claim 1, wherein the step of subjecting the precursor material to a sintering process comprises: And placing the precursor material in an inert atmosphere, heating to 800-900 ℃ at a heating rate of 3-6 ℃ per minute, and preserving heat for 2-12 hours to sinter the precursor material.
  8. 8. The method according to claim 1, wherein the ratio of the sum of the residual carbon content of the organic carbon source and the residual carbon content of the polymer to the mass of the lithium sulfate is (0.21 to 0.22): 1.
  9. 9. A solid electrolyte comprising lithium sulfide produced by the method for producing lithium sulfide according to any one of claims 1 to 8.
  10. 10. A solid-state battery comprising a positive electrode, a negative electrode, and a solid-state electrolyte, wherein the solid-state electrolyte comprises lithium sulfide produced by the method for producing lithium sulfide according to any one of claims 1 to 8.

Description

Preparation method of lithium sulfide, solid electrolyte and solid battery Technical Field The application relates to the technical field of batteries, in particular to a preparation method of lithium sulfide, a solid electrolyte and a solid battery. Background Lithium sulfide has an inverse fluorite crystal structure, and lithium ions migrate in the crystal through tetrahedral and octahedral gaps to form rich transmission channels. The structure can lead the lithium sulfide to achieve the ion conductivity (up to 10 -2 S/cm) close to that of the liquid electrolyte at room temperature, which is obviously higher than that of the oxide electrolyte. Lithium sulfide is a key precursor raw material for synthesizing sulfide solid electrolyte, directly influences the ion conductivity and battery performance ‌ of the solid electrolyte, and restricts the synthesis process and product performance of the subsequent sulfide solid electrolyte. In the solid-state battery, the lithium sulfide as an electrolyte material can enable the energy density of the all-solid-state lithium battery to break through 500Wh/kg (about 300Wh/kg of the traditional lithium battery), inhibit the growth of lithium dendrites and improve the safety. The purity parameter in the product index of lithium sulfide is particularly critical, and has important influence on the preparation of sulfide electrolyte. At present, the production method of lithium sulfide is mainly based on a solid phase method of carbothermic reduction of lithium sulfate, but a large amount of impurities, such as carbon impurities and the like, are generated in the production process, so that the purity of the product lithium sulfide is low, and finally the performance of a sulfide solid electrolyte using the lithium sulfide is influenced. Carbon impurities in lithium sulfide can cause sulfide solid state electrolytes to have some electron conducting capability, which is a negative property for solid state electrolytes to avoid. Therefore, how to improve the purity of lithium sulfide is a technical problem to be solved in the art. Disclosure of Invention Aiming at the defects of the prior art, the application aims to provide a preparation method of lithium sulfide, a solid electrolyte and a solid battery, which can effectively improve the purity of the prepared lithium sulfide. To achieve one or a part or all of the above or other objects, a first aspect of the present application provides a method for producing lithium sulfide, which is characterized in that the lithium sulfide is used for producing a solid electrolyte, comprising the steps of: Uniformly mixing lithium sulfate, an organic carbon source and a high polymer in a solvent to obtain a mixed solution, wherein the mass ratio of the lithium sulfate to the organic carbon source is 1 (0.7-1), the mass ratio of the organic carbon source to the high polymer is 0.7-1 (0.1-2.5), and the ratio of the sum of the residual carbon amount of the organic carbon source and the residual carbon amount of the high polymer to the mass of the lithium sulfate is 0.2-0.25:1; Spray drying the mixed solution to obtain a precursor material; And sintering the precursor material to obtain the product lithium sulfide. Further, the particle size of the precursor material is 1-10 mu m; further, the particle size of the precursor material is 1-5 mu m; further, the particle size of the lithium sulfate is 5 μm or less, and the particle size of the organic carbon source is 1 μm or less. Further, the organic carbon source comprises at least one of glucose, sucrose and citric acid, and/or the high molecular polymer comprises at least one of polyethylene glycol, polyvinyl alcohol and polyoxyethylene. Further, the molecular weight of the high molecular polymer is 400 or less. Further, the solvent is water or ethanol. Further, the air inlet temperature of the spray drying is 100-200 ℃. Further, the step of sintering the precursor material includes: And placing the precursor material in an inert atmosphere, heating to 800-900 ℃ at a heating rate of 3-6 ℃ per minute, and preserving heat for 2-12 hours to sinter the precursor material. Further, the ratio of the sum of the residual carbon content of the organic carbon source and the residual carbon content of the polymer to the mass of the lithium sulfate is (0.21-0.22): 1. The second aspect of the application provides a solid electrolyte comprising lithium sulfide prepared by the method for preparing lithium sulfide. A third aspect of the present application provides a solid-state battery comprising a positive electrode, a negative electrode, and a solid-state electrolyte comprising lithium sulfide produced by the above-described production method of lithium sulfide. According to the preparation method of lithium sulfide, the solid electrolyte and the solid battery, the mixed carbon source of the organic carbon source and the high-molecular polymer is adopted, uniform dispersion of lithium sulfate and the ca