CN-121584012-B - Process for preparing lithium-sulfur electrolyte raw material based on waste salt

CN121584012BCN 121584012 BCN121584012 BCN 121584012BCN-121584012-B

Abstract

The invention relates to the technical field of battery materials and resource recycling, and provides a process for preparing lithium-sulfur electrolyte raw materials based on waste salt, which comprises the steps of taking industrial waste salt as a sulfur source, lithium-rich waste residue as a lithium source, taking waste carbon as a reducing agent, uniformly mixing the waste carbon with a binder, and granulating to obtain mixed particles; further calcining to obtain a mixture, mixing the obtained mixture with the solvent A, performing ball milling, performing solid-liquid separation to obtain a liquid phase containing sulfide, performing acid leaching treatment and condensation on the obtained solid phase to obtain silicon tetrachloride, mixing and dissolving the liquid phase containing sulfide and lithium chloride, performing solid-liquid separation to obtain a solution containing lithium chloride and lithium sulfide, performing reduced pressure concentration on the solution containing lithium chloride and lithium sulfide to obtain a mixed product of lithium chloride and lithium sulfide, and further adjusting the proportion to obtain the lithium-sulfur electrolyte raw material. The invention realizes the resource utilization of industrial waste salt and lithium-rich waste residue, reduces the preparation cost of lithium-sulfur electrolyte raw materials, and simultaneously produces high-value silicon tetrachloride as a byproduct and reduces the emission of waste.

Inventors

CHEN RUNHUA
XIAO JUN
LI ZHAOPENG
QIN ZHAN
JIN ZHIYONG
JIANG YUN

Assignees

中南林业科技大学

Dates

Publication Date: 20260512
Application Date: 20260127

Claims (8)

1. A process for preparing lithium-sulfur electrolyte raw material based on waste salt is characterized by comprising the following steps of Step 1, raw material pretreatment, namely taking industrial waste salt as a sulfur source, lithium-rich waste residue as a lithium source, waste carbon as a reducing agent, uniformly mixing with a binder, and granulating to obtain mixed particles, wherein the lithium-rich waste residue contains lithium sulfate, lithium chloride, lithium carbonate, lithium oxide, lithium hydroxide, silicon dioxide or aluminum oxide; step 2, calcining the mixed particles at a high temperature to obtain a mixture; Ball milling separation, namely mixing the obtained mixture with the solvent A, performing ball milling, and performing solid-liquid separation to obtain a liquid phase containing sulfide and a solid phase containing other substances, wherein the ball milling speed is 100-500r/min, and the ball milling time is 1-6 hours; Step 4, recovering impurities, namely performing acid leaching treatment and condensation on the obtained solid phase containing other substances to obtain silicon tetrachloride, wherein the temperature of the acid leaching treatment is 80-180 ℃ and the time is 1-6 hours; Step 5, sodium removal treatment, namely mixing and dissolving a liquid phase containing sulfide and lithium chloride, and carrying out solid-liquid separation to obtain a solution containing lithium chloride and lithium sulfide; And 6, preparing a product, namely concentrating a solution containing lithium chloride and lithium sulfide under reduced pressure to obtain a mixed product of the lithium chloride and the lithium sulfide, and further regulating the proportion to obtain the lithium-sulfur electrolyte raw material.
2. The process according to claim 1, wherein the main component of the industrial waste salt is sodium sulfate, and the industrial waste salt is derived from nonferrous smelting, chemical industry and new energy industry; The waste carbon is at least one selected from industrial activated carbon waste, raw carbon powder waste, coal gas activated carbon waste, coke waste and biochar; The adhesive is an aqueous solution adhesive prepared from one or more of starch, polyacrylamide and polyaluminium sulfate, The sulfur source, the lithium source, the waste carbon and the binder are adjusted according to the content of sodium sulfate in industrial waste salt, the content of lithium compounds in lithium-rich waste residue and the purity of target products, so that sulfate radicals can be fully reduced in subsequent calcination reactions, and lithium elements can be fully converted into lithium sulfide.
3. The process according to claim 1, wherein the particle size of the mixed particles is 1-15cm; the calcination is carried out in a muffle furnace or rotary kiln calcination equipment; the calcination temperature is 900-1500 ℃; The calcining atmosphere can adopt inert gas protection or closed atmosphere; The calcination time is 1-6 hours.
4. The process according to claim 1, wherein the solid-to-liquid ratio of the mixture to the solvent A is 1 (5-10) (g/mL).
5. The process of claim 1, wherein the solvent a is at least one of C 1-6 alcohol solvent a, tetrahydrofuran, hexamethylphosphoramide, or ethylene glycol.
6. The process of claim 1, wherein the acid is one or more of hydrochloric acid, perchloric acid, nitric acid, or sulfuric acid; The acid concentration is 1-12mol/L.
7. The process according to claim 1, wherein the lithium chloride is used in an amount of 0.3 to 0.6 times the mass of the liquid phase containing the sulfide; The process of mixing and dissolving is that stirring and reacting for 0.5-2 hours at the low temperature of 0-10 ℃ and the rotating speed of 100-200 r/min; The reduced pressure concentration condition is that rotary steaming treatment is carried out under the conditions of 40-80 ℃ and 0.05-0.09 MPa.
8. The process of claim 1, wherein the mixed product is used to adapt the formulation requirements of a solid lithium sulfur electrolyte having a molar ratio of lithium sulfide, lithium chloride, phosphorus pentasulfide of 4:3:1 or 5:2:1.

Description

Process for preparing lithium-sulfur electrolyte raw material based on waste salt Technical Field The invention relates to the technical field of battery materials and resource recycling, and provides a process for preparing lithium-sulfur electrolyte raw materials based on waste salt. Background Along with the rapid development of new energy industry, the solid-state lithium sulfur battery becomes a research hot spot due to the advantages of high energy density, good safety and the like, and lithium sulfide, lithium chloride and the like are key raw materials of the solid-state lithium sulfur electrolyte. At present, the preparation of lithium sulfide and lithium chloride mostly uses a pure reagent as a raw material, the production cost is high, and certain waste can be generated in the production process to pollute the environment. On the other hand, a large amount of industrial waste salts (mainly comprising sodium sulfate) are generated in the industries of nonferrous smelting, chemical industry, new energy and the like, if the waste salts are directly discharged, soil and water pollution is caused, the treatment difficulty is high, meanwhile, the lithium-rich waste residues generated in the lithium extraction industry contain a certain amount of lithium compounds, but the waste of resources and the environmental pressure are caused by the fact that the recycling difficulty is high due to the fact that the content of impurities is high. In the prior art, little research is carried out on the preparation of electrolyte raw materials by recycling industrial wastes, and a process for simultaneously and efficiently utilizing industrial waste salts and lithium-rich waste residues, directly preparing lithium chloride-lithium sulfide mixed raw materials meeting the requirements of solid lithium sulfur electrolytes and preparing high-value products as byproducts does not appear. Therefore, the development of the process for preparing the lithium sulfur electrolyte raw material based on the waste salt, which has the advantages of high resource utilization rate, low cost and environmental friendliness, has important practical significance. Disclosure of Invention Aiming at the problems in the background art, the main purpose of the invention is to provide a process for preparing lithium-sulfur electrolyte raw materials based on waste salt, which comprises six steps of raw material pretreatment, high-temperature calcination, ball milling separation, impurity recovery, sodium removal treatment and product preparation, so that the resource utilization of industrial waste salt and lithium-rich waste residues is realized, the preparation cost of the lithium-sulfur electrolyte raw materials is reduced, and meanwhile, high-value silicon tetrachloride is produced as a byproduct, and the waste emission is reduced. In a first aspect, the present invention provides a process for preparing a lithium sulfur electrolyte raw material based on waste salt, comprising Step 1, raw material pretreatment, namely uniformly mixing industrial waste salt serving as a sulfur source, lithium-rich waste residue serving as a lithium source and waste carbon serving as a reducing agent with a binder, and granulating to obtain mixed particles; step 2, calcining the mixed particles at a high temperature to obtain a mixture; Ball milling separation, namely mixing the obtained mixture with the solvent A, ball milling, and carrying out solid-liquid separation to obtain a liquid phase containing sulfide and a solid phase containing other substances; Step 4, recovering impurities, namely performing acid leaching treatment and condensation on the obtained solid phase containing other substances to obtain silicon tetrachloride; Step 5, sodium removal treatment, namely mixing and dissolving a liquid phase containing sulfide and lithium chloride, and carrying out solid-liquid separation to obtain a solution containing lithium chloride and lithium sulfide; And 6, preparing a product, namely concentrating a solution containing lithium chloride and lithium sulfide under reduced pressure to obtain a mixed product of the lithium chloride and the lithium sulfide, and further regulating the proportion to obtain the lithium-sulfur electrolyte raw material. In some embodiments, the main component of the industrial waste salt is sodium sulfate, and the industrial waste salt is derived from nonferrous smelting, chemical industry and new energy industry. In some embodiments, the lithium-rich waste residue comprises lithium sulfate, lithium chloride, lithium carbonate, lithium oxide, lithium hydroxide, silica, or alumina, or the like. In some embodiments, the waste carbon is selected from at least one of industrial activated carbon waste, raw carbon powder waste, coal gas activated carbon waste, coke waste, biochar. In some embodiments, the binder is an aqueous binder formulated with one or more of starch, polyacrylamide, polyaluminum sulfate, to increase viscosity a