Lithium Sulfide Production Using Inexpensive Precursors
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Solution Overview
Problem
Existing methods for producing Lithium Sulfide (Li2S) are costly due to the use of expensive precursors and equipment, and often result in low-purity products.
Innovation Solution
A method involving the combination of Li2Sx and Na2S in a solvent, with the addition of elemental sulfur and lithium salts, to form a high-purity Li2S product using inexpensive precursors and scalable processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional synthetic routes are used to produce Li2S, then the production process can be established, but the cost increases due to expensive precursors and equipment
Solution Approach 1:
The patent replaces expensive precursors (lithium metal, lithium organic compounds) with inexpensive alternatives (lithium halide salts, sodium sulfide). The method uses readily available, low-cost materials to synthesize Li2S, eliminating the need for costly starting materials while maintaining product purity and yield.
Solution Approach 2:
The patent changes the chemical parameters of the reaction system by using lithium halide salts and sodium sulfide in aprotic solvents at moderate temperatures, rather than the high-purity lithium metal and high-temperature conditions required by traditional methods. This parameter change enables cost-effective production without sacrificing product quality.
2Productivity
If traditional synthetic routes are used to produce Li2S, then the production can proceed, but the product purity decreases
Solution Approach 1:
The patent introduces a two-step reaction mechanism with an intermediate lithium polysulfide stage. First, lithium halide reacts with sulfur to form lithium polysulfide, which then reacts with sodium sulfide to produce high-purity Li2S. This intermediary step enables precise control over the reaction process and product purity, avoiding the hydrolysis issues that plague aqueous methods.
Solution Approach 2:
The patent employs aprotic solvents (such as acetonitrile, dimethyl carbonate, ethyl methyl carbonate) that create an inert reaction environment preventing hydrolysis of lithium sulfide. This inert environment maintains product purity by excluding water and oxygen from the reaction system, eliminating the need for complex purification steps.
3Object-generated harmful factors
If Barker's method is used, then less expensive precursors are utilized, but expensive specialized processing equipment is required due to corrosive nature
Solution Approach 1:
The patent uses aprotic solvents that create a non-corrosive reaction environment, eliminating the need for specialized corrosion-resistant equipment. The inert solvent system prevents aggressive chemical interactions with reactor walls and processing equipment, allowing the use of standard, cost-effective manufacturing equipment while maintaining low precursor costs.
4Object-generated harmful factors
If Mehta's method is used, then less expensive precursors are used, but high temperatures and aqueous solution lead to hydrolysis and lower purity
Solution Approach 1:
The patent replaces aqueous solutions with aprotic solvents, creating an inert environment that prevents hydrolysis of lithium sulfide. This solvent substitution maintains low precursor costs while ensuring high product purity by eliminating water-induced decomposition reactions.
Solution Approach 2:
The patent modifies the temperature parameter by conducting reactions at moderate temperatures rather than high temperatures, and changes the solvent parameter from aqueous to aprotic. These parameter changes simultaneously reduce precursor costs and prevent hydrolysis, achieving both economic and purity goals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high-purity Li2S production with reduced costs and environmental impact, utilizing recyclable materials and minimizing the generation of toxic gases.
Implementation Method 1
combining Li2Sx and Na2S in a solvent to form a mixture... reacting to form a precipitate of Na2Sx and a reaction product of Li2S
Implementation Method 2
combining Li2Sx and Na2S in a solvent to form a mixture
Implementation Method 3
heat is applied to remove the solvent
Implementation Method 4
isolating unreacted Li2Sx and heating the Li2Sx to form Li2S
Data Source
AI summary
Provided herein are methods for making Li2S. The method includes combining metal polysulfides, metal sulfides, metal salts, elemental sulfur in a solvent to form a mixture and isolating Li2S from the mixture. Provided herein are also methods for purifying the isolated Li2S forming a high-purity Li2S. Further provided herein are methods for making solid-state electrolytes.