Li2S Purification via Dense Solvent Separation
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Solution Overview
Problem
There is a need for efficient and cost-effective methods to synthesize lithium sulfide (Li2S) with high yield, as its increased use in solid-state batteries requires improved production techniques.
Innovation Solution
The method involves combining an alkali metal sulfide, a lithium salt, an alcohol, and a hydrocarbon to form a mixture, followed by adding a solvent with a density higher than 1.67 g/cm3 to separate and isolate the Li2S reaction product, which can be skimmed or filtered from the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional Li2S synthesis methods are used, then production cost and complexity are reduced, but Li2S yield and purity are insufficient for high-performance solid-state batteries
Solution Approach 1:
The synthesis process is divided into distinct stages: initial reaction phase, precipitation phase, and separation phase. Each phase uses optimized conditions (temperature, solvent composition, addition rate) to achieve specific objectives, resulting in high-purity Li2S with minimal contamination
Solution Approach 2:
The patent systematically varies critical parameters including solvent density (using solvents denser than 1.67 g/cm³), temperature profiles, and reactant ratios to optimize Li2S precipitation and separation efficiency, achieving both high purity and simplified processing
2Productivity
If conventional Li2S synthesis methods are used, then equipment and operational requirements are minimized, but production yield is insufficient to meet growing battery demand
Solution Approach 1:
A dense non-aqueous solvent acts as an intermediary medium that facilitates complete reaction between lithium source and sulfur source, enables efficient precipitation of Li2S, and simplifies separation from byproducts. The solvent's high density (>1.67 g/cm³) is critical for achieving rapid phase separation and high recovery yields
Solution Approach 2:
The patent employs composite solvent systems combining dense solvents with specific density ranges, optimizing both reaction efficiency and separation performance. This composite approach maximizes Li2S yield while maintaining manufacturing simplicity through enhanced phase discrimination
3Manufacturing precision
If conventional Li2S synthesis methods are used, then process time and energy consumption are reduced, but separation efficiency and Li2S recovery are insufficient
Solution Approach 1:
The patent replaces complex mechanical separation systems with a density-based gravitational separation mechanism. The dense solvent causes Li2S to precipitate and settle naturally, eliminating the need for extensive filtration, centrifugation, or other time-consuming mechanical separation operations
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
This method enables the efficient separation and isolation of Li2S, enhancing its yield and potentially reducing production costs, thus addressing the growing demand for Li2S in solid-state battery applications.
Implementation Method 1
adding to the mixture a solvent having a density higher than 1.67 g/cm3; and, isolating a Li2S reaction product from the mixture
Implementation Method 2
evaporating less than 50% of the alcohol, or evaporating less than 25% of the alcohol, or evaporating less than 10% of the alcohol, or evaporating less than 7% of the alcohol, or evaporating less than 5% of the alcohol
Data Source
AI summary
Provided herein are methods of preparing Li2S. The methods generally include combining an alkaline metal sulfide, a lithium salt, an alcohol, and a hydrocarbon to form a mixture. A reaction forms the Li2S. A dense solvent is then added to the mixture and the Li2S is isolated from the mixture.