Method for synthesizing lithium sulfide

Abstract

The invention mainly relates to the field of lithium battery materials, and provides a method for synthesizing lithium sulfide by taking a lithiation solution and elemental sulfur as raw materials through direct reaction, which comprises the following steps: preparing the lithiation solution, an organic ether solution containing a metal lithium-aromatic compound, a lithium iodide solution and an n-butyl lithium solution; adding elemental sulfur into the lithiation solution for mixing; and sequentially carrying out a room-temperature reaction, separation and precipitation, drying and heat treatment on the mixed solution to obtain the lithium sulfide. The synthesis method of lithium sulfide has the advantages of cheap and easily available raw materials, simple process, no harmful gas generation, and mild and controllable synthesis process.

Description

technical field [0001] The invention belongs to the field of lithium battery materials, and in particular relates to a method for synthesizing lithium sulfide. Background technique [0002] Solid-state electrolytes are generally divided into three categories: polymers, oxides, and sulfides. Solid-state batteries using polymer electrolytes are close to existing lithium-ion batteries in terms of manufacturing process, but the conductivity of polymer electrolytes at room temperature is low. Oxide electrolytes have good thermal, chemical, and electrochemical stability, but their room temperature ionic conductivity is limited to 10 −3 –10 −4 S / cm and leads to poor interfacial contact with electrode materials due to its high rigidity. Sulfide electrolytes have high lithium-ion conductivity and good interfacial contact due to relatively "soft" mechanical properties, so they are currently the most research-worthy electrolyte systems. Lithium sulfide is an indispensable raw mater...

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Problems solved by technology

The above-mentioned synthesis process uses toxic hydrogen sulfide as a raw material, which has high requirements for equipment and process control, which is not conducive to the safety of the preparation process

(2) Using elemental sulfur as the sulfur source: the patent with the notification number CN106784754B dissolves sublimated sulfur powder in anhydrous toluene and reacts with tetrahydrofuran solution mixed with carbon nanotubes and lithium triethylborohydride to prepare carbon nanotubes-lithium sulfide Composite material powder, but the cost of the raw material lithium triethyl borohydride used is relatively high

(3) Using carbon disulfide as a source of sulfur: the patent with the notification number CN103764566B utilizes elemental lithium and elemental sulfur and / or is selected from CS 2 , COS, SO 2 , SO sulfur-containing compounds are in a liquid state and react in an aliphatic or cycloaliphatic hydrocarbon solvent to prepare carbon-coated lithium sulfide. The solvent used in this synthesis method must be in a liquid state at the reaction temperature and the reaction temperature is between 80 ° C and 200 ° C. Therefore The selectivity of the solvent is small

The patent application with publication number CN108358175A dissolves lithium sulfide, sulfur-rich compounds (one or more of sulfur and sulfur-rich compounds), metal lithium and aromatic compounds in ether organic solvents, and reacts to obtain lithium sulfide, but the The synthesis process needs to first react lithium sulfide with sulfur-rich compounds and dissolve them in ether organic solvents to obtain unsaturated Li2S x Solution (1<x≤8), the synthesis process is more complicated

The patent application whose publication number is CN109019526A utilizes an organic solvent method to prepare lithium sulfide, dissolves metallic lithium and sulfur in organic solvents respectively, and finally mixes and reacts at low temperature to obtain lithium sulfide, but the solvent selection of this synthesis method is limited (ethylenediamine and At least one of propylenediamine), and it is required to react in a jacketed reactor and pass cooling water into the jacket, and the preparation conditions are relatively harsh

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