Lithium Sulfide Production Suppressing Polysulfides
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Solution Overview
Problem
Conventional methods for producing lithium compositions used in sulfide solid electrolyte materials often generate polysulfides during the sulfurization treatment, leading to impurities in the final product.
Innovation Solution
A method involving the formation of lithium sulfide (Li2S) and lithium iodide (LiI) through specific aqueous solution steps, including reacting iodine with a reducing aqueous solution containing calcium oxide and formic acid at circumneutral pH, followed by sulfurization and hydrogen sulfide elimination, to suppress polysulfide generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sulfurization treatment is used to produce lithium composition, then lithium sulfide can be obtained, but polysulfides are generated as impurities
Solution Approach 1:
The patent applies preliminary action by conducting the sulfurization treatment at a controlled temperature range of 100°C to 150°C, which is below the decomposition temperature of lithium iodide. This preliminary control of reaction conditions prevents polysulfide generation before it can occur, thereby obtaining high-purity lithium sulfide without the harmful polysulfide byproducts
Solution Approach 2:
The patent changes the temperature parameter to resolve the contradiction. By maintaining the sulfurization temperature between 100°C and 150°C, the process achieves complete sulfurization of lithium hydroxide to lithium sulfide while preventing lithium iodide decomposition and polysulfide formation. This precise parameter control enables high-purity product production
2Productivity
If temperature is increased to accelerate sulfurization reaction, then reaction speed increases, but lithium iodide decomposes and polysulfides form
Solution Approach 1:
The patent optimizes the temperature parameter to 100°C-150°C, which provides the optimal balance between reaction speed and product purity. This temperature range is sufficient to accelerate the sulfurization reaction while remaining below the decomposition point of lithium iodide, thereby preventing polysulfide formation and maintaining high manufacturing precision
Solution Approach 2:
The patent performs preliminary optimization of reaction conditions before conducting the sulfurization treatment. By pre-establishing the temperature window of 100°C-150°C and controlling the addition rate of sulfurizing agent, the process ensures rapid reaction proceeds without exceeding safe temperature limits that would cause decomposition and impurity formation
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 effectively reduces the generation of polysulfides, resulting in a lithium composition that produces sulfide solid electrolyte materials with fewer impurities, enhancing their purity and performance.
Implementation Method 1
reacting iodine with a reducing aqueous solution containing calcium oxide, formic acid, and water under a condition of a pH of 5.5 or more and a pH of 10.21 or less through heating
Implementation Method 2
forming the lithium sulfide (Li2S) by sulfurizing the lithium hydroxide (LiOH) to form lithium hydrosulfide (LiHS) and then eliminating hydrogen sulfide from the lithium hydrosulfide (LiHS)
Data Source
AI summary
A method for producing a lithium composition capable of suppressing the generation of polysulfides is provided. The method for producing a lithium composition includes a first aqueous solution forming step of forming a first aqueous solution by reacting iodine with a reducing aqueous solution containing calcium oxide, formic acid, and water under a condition of a pH of 5.5 or more and a pH of 10.21 or less through heating, a second aqueous solution forming step of forming a second aqueous solution by adding calcium oxide to the first aqueous solution, a third aqueous solution forming step of forming a third aqueous solution by adding lithium carbonate to the second aqueous solution, and a Li2S forming step of forming the lithium sulfide (Li2S) by sulfurizing lithium hydroxide (LiOH) to form lithium hydrosulfide (LiHS) and then eliminating hydrogen sulfide from lithium hydrosulfide (LiHS).