Lithium Sulfide Synthesis via Wet-Dry H2S Conversion of LiOH
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Solution Overview
Problem
Conventional methods for producing lithium sulfide face challenges such as the agglomeration of hygroscopic lithium hydroxide, difficulty in processing into fine particles, and the inability to mass-produce high-purity lithium sulfide due to low carbon adsorption and high process costs.
Innovation Solution
A method involving a series of reactions at elevated pressures and temperatures, combined with the use of organic solvents and hydrogen sulfide gas, including primary, secondary, tertiary, and quaternary reactions, to convert lithium hydroxide into lithium sulfide through a wet and dry process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium hydroxide is used as a reactant in the dry process, then lithium sulfide can be synthesized through reaction with hydrogen sulfide, but lithium hydroxide easily agglomerates due to high hygroscopy, making it difficult to handle and process into fine particles
Solution Approach 1:
The invention changes the physical state of lithium hydroxide from solid particles to aqueous solution, fundamentally altering its handling properties. The lithium hydroxide solution eliminates agglomeration issues inherent to solid LiOH while enabling mass production through controlled reaction with hydrogen sulfide gas.
Solution Approach 2:
The invention introduces hydrogen sulfide gas as a reactant, using gas-liquid reaction methodology. The H2S gas is bubbled through the lithium hydroxide solution, enabling controlled reaction and product formation while avoiding the handling difficulties of solid lithium hydroxide.
2Manufacturing precision
If conventional dry process is used to synthesize lithium sulfide, then the reaction can proceed at elevated temperatures, but it is difficult to mass-produce high-purity lithium sulfide with fine particles
Solution Approach 1:
The invention changes the reaction medium from dry solid-state to aqueous solution, enabling better control over reaction conditions. This parameter change allows for continuous processing and mass production while maintaining high purity through controlled reaction stoichiometry and temperature management.
Solution Approach 2:
The invention divides the synthesis process into controlled stages: reaction of H2S gas with LiOH solution to form Li2S, followed by separate purification and drying steps. This segmentation enables each step to be optimized independently for both purity and production efficiency.
3Use of energy by moving object
If sulfur is used as cathode material in lithium-sulfur batteries, then the energy density can be increased, but the low sublimation temperature of sulfur requires ampoule usage and repeated carbon adsorption processes, resulting in high process costs
Solution Approach 1:
The invention extracts sulfur from its elemental form and converts it to lithium sulfide compound through chemical reaction. This extraction of sulfur from its problematic native state and transformation into a stable compound eliminates the need for ampoules and repeated carbon adsorption processes.
Solution Approach 2:
The invention changes the chemical form of sulfur from elemental sulfur (low sublimation temperature) to lithium sulfide (high melting point material). This parameter change in chemical composition fundamentally alters the thermal properties, eliminating processing complexities while maintaining the high energy density benefit.
4Ease of operation
If lithium metal is used as anode material, then the battery can operate, but lithium metal grows into dendrite phase during charging and discharging, causing short circuit and lowering battery stability
Solution Approach 1:
The invention uses the chemical reactivity of lithium (which causes dendrite formation in metallic form) and converts it into a beneficial property by forming lithium sulfide compound. The compound form maintains lithium's electrochemical activity while eliminating the mechanical dendrite growth problem, converting a harmful characteristic into a useful one.
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
Enables the mass-production of high-purity lithium sulfide with purities above 99.9%, overcoming the limitations of conventional methods by ensuring complete conversion of lithium hydroxide and minimizing impurities.
Implementation Method 1
allowing a primary reaction at a pressure higher than normal pressure by raising a temperature of a reaction solution containing lithium hydroxide (LiOH) and an organic solvent to 100° C. or above and then injecting hydrogen sulfide (H2S) gas into the reaction solution
Implementation Method 2
allowing a secondary reaction one more times by injecting hydrogen sulfide (H2S) gas when an internal pressure of a reactor returns to normal pressure after step a
Implementation Method 3
obtaining a primary reaction product by removing the organic solvent from the reaction solution after step b)
Implementation Method 4
allowing a quaternary reaction, one or more times after step d, by removing water, which is a reaction by-product, using a vacuum pump and then injecting hydrogen sulfide (H2S) gas
Data Source
AI summary
The present invention relates to a method of preparing high-purity lithium sulfide through wet and dry processes. More particularly, the present invention provides a lithium sulfide preparation method including a wet process of reacting lithium hydroxide (LiOH) with hydrogen sulfide (H2S) gas in an organic solvent and a dry process of reacting a dried reaction product resulting from the wet process with hydrogen sulfide (H2S) gas. The lithium sulfide preparation method enables mass production of lithium sulfide.