Lithium Sulfide Preparation Using Metallic Lithium for Lower-Cost Purity
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Solution Overview
Problem
The high cost and limited availability of lithium sulfide restrict the widespread adoption of sulfide solid-state batteries, while liquid batteries face issues of electrochemical and thermal instability and safety concerns.
Innovation Solution
A method involving the reaction of metallic lithium with sulfur at controlled temperatures (250-300°C) followed by ball-milling and purification with a specific solvent mixture to produce high-purity lithium sulfide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lithium sulfide is prepared by conventional methods, then high purity lithium sulfide can be obtained, but the production cost is extremely high (10 million yuan/ton)
Solution Approach 1:
The patent changes the reaction parameters by conducting the reaction at room temperature instead of high temperatures, and by controlling the molar ratio of lithium to sulfur (1:0.8-1:1). It also changes the physical state parameters by using ball-milling to achieve fine mixing and increase reaction efficiency, thereby obtaining high-purity lithium sulfide at low cost
Solution Approach 2:
The patent uses inexpensive raw materials (metallic lithium and sulfur powder) and simple equipment (ball-milling device, vacuum drying device) to replace expensive conventional preparation methods, achieving production cost below 500,000 yuan/ton while maintaining high product purity
2Reliability
If liquid batteries are used, then high conductivity is achieved, but electrochemical and thermal stability are insufficient and safety is poor
Solution Approach 1:
The patent prepares lithium sulfide through controlled reaction of metallic lithium with sulfur, producing a composite material with optimized crystal structure. The ball-milling process creates fine-grained composite structure that enhances both stability and conductivity properties of the resulting lithium sulfide
3Productivity
If the reaction temperature is increased to accelerate the reaction between metallic lithium and sulfur, then reaction speed increases, but violent heat release occurs
Solution Approach 1:
The patent performs preliminary ball-milling of lithium and sulfur before the reaction to achieve fine and uniform mixing at the molecular level. This preliminary mechanical activation increases the reaction surface area and promotes gentle reaction at room temperature, avoiding violent heat release while maintaining high reaction efficiency
Solution Approach 2:
The patent changes the reaction temperature parameter from high temperature to room temperature, and controls the molar ratio of reactants (Li:S = 1:0.8-1:1) to ensure complete reaction without excess reactivity, thereby preventing violent heat release while achieving fast reaction through ball-milling enhancement
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 significantly reduces production costs, enhances safety, and produces lithium sulfide with high purity and fine crystallinity suitable for industrial applications.
Implementation Method 1
metallic lithium and sulfur are difficult to react at room temperature. When the two substances are in a liquid state at 250-300° C., their contact angles can be increased, and thus a reaction will occur
Implementation Method 2
performing ball-milling at room temperature at a rotation speed of 100-500 r/min for 12-24 h; the ball-milled lithium sulfide has finer primary particles and a better crystalline state
Implementation Method 3
adding the obtained ball-milled lithium sulfide into a mixed solution of isopropanol/xylene according to a mass-to-volume ratio of 1:5, and stirring for 1-2 h; the excess sulfur powder will be dissolved in xylene
Implementation Method 4
the residual metallic lithium will react with isopropanol
Implementation Method 5
placing the obtained lithium sulfide wet material into a vacuum drying oven at 205° C., and drying in vacuum for 8-12 h
Data Source
AI summary
A method for preparing lithium sulfide by using metallic lithium includes steps A-D. The step A includes placing 0.05-0.1 kg of the metallic lithium and a first sulfur powder into a sealed container under an inert condition according to a mass ratio of the metallic lithium to the first sulfur powder being 1:0.8-1:1. The step B includes placing the sealed container into a vacuum oven at 250-300° C. and holding for 2-3 h, then adding second first sulfur powder and heating at 250-300° C. for 2-3 h, and finally adding first sulfur powder and heating at 250-300° C. for 2-3 h to obtain a crude lithium sulfide product. The step C includes ball-milling on the crude lithium sulfide product to obtain a ball-milled lithium sulfide. The step D includes adding the ball-milled lithium sulfide into a mixed solution of isopropanol and xylene to obtain a lithium sulfide slurry.