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CN-121672426-B - Method for preparing lithium sulfide by taking diethyl sulfide as sulfur source, product and application thereof

CN121672426BCN 121672426 BCN121672426 BCN 121672426BCN-121672426-B

Abstract

The invention provides a method for preparing lithium sulfide by taking diethyl sulfide as a sulfur source, and a product and application thereof, and belongs to the technical field of compound synthesis. The method takes diethyl sulfide as a sulfur source and lithium metal as a lithium source, and comprises the specific steps of preparing a substituted biphenyl lithium complex, dropwise adding diethyl sulfide into a substituted biphenyl lithium complex system, carrying out reduction reaction at 60-70 ℃, and carrying out solid-liquid separation, washing, vacuum distillation to remove impurities and drying to obtain the high-purity lithium sulfide. The invention innovatively adopts a washing-vacuum distillation composite purification process, the purity of the obtained product is more than or equal to 99.9%, the moisture is less than or equal to 30ppm, the D50 particle size is less than or equal to 5 mu m, the reaction condition is mild, the byproducts are easy to treat, the cost is controllable, the problems of high raw material toxicity, difficult removal of the byproducts and the like in the prior art are effectively solved, and the method is suitable for preparing all-solid-state battery electrolyte precursors and has industrialized amplification potential.

Inventors

  • YANG YANG
  • XI JINXU
  • XU CHAO
  • ZHAN QIAN
  • ZHU LINGYUN
  • SUN ZHENJIE

Assignees

  • 安徽金禾合成材料研究院有限公司
  • 安徽金禾实业股份有限公司

Dates

Publication Date
20260508
Application Date
20260210

Claims (20)

  1. 1. A method for preparing lithium sulfide by taking diethyl sulfide as a sulfur source is characterized by comprising the following steps: S1, preparing a lithium complex, namely dissolving substituted biphenyl in dried ethylene glycol dimethyl ether under the inert gas atmosphere to obtain a substituted biphenyl solution, adding metal lithium into the solution, and stirring at room temperature to obtain a lithium complex solution; s2, a reduction reaction, namely dripping diethyl sulfide into the lithium complex solution prepared in the step S1 at a constant rate to perform the reduction reaction to obtain a suspension; S3, solid-liquid separation and preliminary purification, namely carrying out vacuum suction filtration on the suspension obtained in the step S2, and collecting solid phase sediment; s4, deep impurity removal by vacuum distillation, namely placing the solid phase precipitate washed in the step S3 into a vacuum distillation device for vacuum distillation to obtain a pre-product; s5, drying and preparing a finished product, namely placing the pre-product obtained in the step S4 into a vacuum drying oven for drying to obtain a high-purity lithium sulfide product; The substituted biphenyl in the step S1 is one or more of 4,4' -dimethylbiphenyl, 2-methylbiphenyl or 3,3', 4' -tetramethylbiphenyl; the mol ratio of diethyl sulfide to lithium metal in the step S2 is 1:4-4.5; In the step S4, a temperature programming mode is adopted in the vacuum distillation process, and the temperature programming rate is controlled to be 5 ℃ per minute.
  2. 2. The method according to claim 1, wherein the substituted biphenyl in step S1 is 3,3', 4' -tetramethylbiphenyl.
  3. 3. The method according to claim 1, wherein the drying in step S1 is performed by using molecular sieves, and the moisture content of the dried ethylene glycol dimethyl ether is controlled to be less than 30 ppm.
  4. 4. The method of claim 3, wherein the molecular sieve is a 4A molecular sieve.
  5. 5. The method of claim 3, wherein the concentration of the substituted biphenyl solution is 0.5-1.5mol/L.
  6. 6. The method according to claim 5, wherein the concentration of the substituted biphenyl solution is 0.8-1.2mol/L.
  7. 7. The method of claim 6, wherein the concentration of the substituted biphenyl solution is 1.0mol/L.
  8. 8. The method of claim 1, wherein the molar ratio of the lithium metal to the substituted biphenyl is 1:1-1.2.
  9. 9. The method of claim 8, wherein the molar ratio of the lithium metal to the substituted biphenyl is 1:1-1.1.
  10. 10. The method of claim 9, wherein the molar ratio of lithium metal to substituted biphenyl is 1:1.
  11. 11. The method according to claim 1, wherein the stirring time in the step S1 is 2 to 4 hours.
  12. 12. The method according to claim 1, wherein the diethyl sulfide is added in step S2 at a rate of 0.5 to 1mL/min.
  13. 13. The method according to claim 12, wherein the diethyl sulfide is added in step S2 at a rate of 0.6-0.8mL/min.
  14. 14. The method according to claim 13, wherein the diethyl sulfide is added at a rate of 0.8mL/min in step S2.
  15. 15. The method according to claim 1, wherein the molar ratio of diethyl sulfide to lithium metal in step S2 is 1:4.2.
  16. 16. The method according to claim 1, wherein the temperature of the reduction reaction in step S2 is 60-70 ℃.
  17. 17. The method according to claim 16, wherein the temperature of the reduction reaction in step S2 is 65 ℃.
  18. 18. The method according to claim 1, wherein the reduction reaction in step S2 is carried out for 3 to 5 hours.
  19. 19. The method of claim 1, wherein the vacuum degree of vacuum filtration in the step S3 is 0.006-0.06MPa.
  20. 20. The method according to claim 1, wherein the washing in the step S3 is performed by using anhydrous tetrahydrofuran, and the number of times of washing is 2-3, and the washing time is 20-30 minutes each time.

Description

Method for preparing lithium sulfide by taking diethyl sulfide as sulfur source, product and application thereof Technical Field The invention belongs to the technical field of compound synthesis, and particularly relates to a method for preparing lithium sulfide by taking diethyl sulfide as a sulfur source, and a product and application thereof. Background Li 2 S is a typical inorganic compound, which belongs to the binary lithium salts and has a face-centered cubic crystal structure. Li 2 S is white or light yellow crystal at normal temperature and normal pressure, has a melting point of about 938 ℃ and a density of about 1.67g/cm 3, and has higher thermal stability and chemical stability. The lithium hydroxide and hydrogen sulfide gas are stable in inert atmosphere, are not easy to react with oxygen at room temperature, have reducibility at high temperature, can react with water to generate lithium hydroxide and hydrogen sulfide gas, and have strong hydrolyzability. Therefore, the preparation, storage and application processes must be tightly controlled with respect to ambient humidity and oxygen content. Li 2 S is a functional material with high theoretical specific capacity, high energy density and interface stability, and has wide application prospect in a plurality of high-performance fields, and is particularly important in an electrochemical energy storage system. In a new generation battery system such as a lithium sulfur battery and an all-solid-state battery, li 2 S can be used as a precursor of a positive electrode material or can participate in constructing a composite solid-state electrolyte under certain conditions. The charge excitation process of Li 2 S typically involves electrochemical reactions of the lithium ion battery, during which lithium ions migrate from the negative electrode to the positive electrode, and during excitation, electron transfer and chemical reactions also affect the lithiation process. the high-energy-density sulfide electrolyte has the advantages that the conductivity is obviously improved under the high-temperature condition, good interface matching can be formed with various sulfide electrolytes, and the high-energy-density sulfide electrolyte is an important basic material for realizing high energy density, safety and service life. In addition to battery systems, li 2 S plays a special role in the fields of thermoelectric materials, organic synthesis and functional ceramics. In the thermoelectric conversion direction, li 2 S is introduced into solid solutions such as Li-Sn-S, so that the carrier mobility and the thermoelectric figure of merit (ZT) can be effectively improved, and the method is suitable for high-temperature thermoelectric devices. In the fields of fine chemical engineering and drug synthesis, li 2 S is used as a sulfur source with high reactivity, can be used for constructing various sulfur-containing organic molecules such as thioether, sulfamide and ligand functional materials, and has unique advantages in high-selectivity synthesis and directional catalytic reaction. In battery technology, li 2 S applications have focused on lithium sulfur batteries and all-solid-state battery systems. Unlike a lithium metal anode, li 2 S has higher chemical stability and lower reactivity, is favorable for improving the safety of battery assembly, and avoids the safety risks of easy dendrite formation, short circuit induction and the like of lithium metal. In a lithium sulfur battery, li 2 S can be used as a pre-lithiated positive electrode precursor, the theoretical specific capacity of the lithium sulfur battery is far higher than that of a traditional oxide or phosphate positive electrode material, and the overall energy density can be greatly improved. In an all-solid-state system, the interface matching property of Li 2 S and a typical sulfide electrolyte is good, and the method is suitable for constructing a continuous ion channel structure and is beneficial to improving the charge transfer efficiency and the interface stability. The composite battery structure is particularly suitable for application scenes such as aerospace, military equipment, high-end electric automobiles and the like with extremely high requirements on energy density, safety and stability. However, in high performance battery applications, stringent requirements are placed on the purity and structure of the Li 2 S material. The presence of trace impurities, such as Li 2CO3、LiOH、Li2SO4, can interfere with electrode interface stability and increase side reaction propensity, thereby affecting cell cycle life and coulombic efficiency. Therefore, the reaction conditions are required to be strictly controlled in the material synthesis process, the purity of the product is ensured, and the uniform particle size distribution, pure crystal form and no impurity phase are realized. The high-purity Li 2 S material also has good micro-nano structure regulation and control capability, so