Continuous LiFSI Crystallization Process for Low-Moisture Purity
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Solution Overview
Problem
The existing methods for producing lithium bis(fluorosulfonyl)imide (LiFSI) face challenges such as low product purity, high moisture content, high production costs, and excessive waste generation, making them unsuitable for industrial-scale production.
Innovation Solution
A continuous method involving steps like reaction of sulfuryl fluoride, ammonia, and triethylamine, followed by evaporation, extraction, alkalinization, dehydration, desolventization, crystallization, and drying, which includes recycling of solvents and by-products, to produce high-purity LiFSI with reduced water content and lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional batch synthesis methods are used for LiFSI production, then the process is simple to operate, but the production time is long, product purity is low, and moisture content is high
Solution Approach 1:
The continuous production process is divided into multiple independent modules including reaction section, extraction section, evaporation section, and crystallization section. Each module performs a specific function and can be independently optimized, enabling high purity product production while maintaining operational simplicity through modular design.
Solution Approach 2:
The patent implements continuous production where reactants continuously flow through the reaction section, and products continuously move through extraction, evaporation, and crystallization sections. This eliminates batch processing interruptions, significantly reducing production time while maintaining high product purity through consistent process parameters.
2Productivity
If traditional synthesis methods are used, then fewer equipment investments are required, but production cost is high and waste generation is large
Solution Approach 1:
The continuous production process incorporates recycling loops where solvents and unreacted materials are continuously recovered and returned to the reaction section. This significantly reduces raw material consumption and waste generation while maintaining high production efficiency through continuous operation.
Solution Approach 2:
Continuous operation eliminates the start-stop cycles of batch processing, maintaining optimal reaction conditions throughout production. This continuous action improves productivity while reducing overall material consumption through better process control and reduced idle time.
3Manufacturing precision
If multiple purification steps are added to improve purity, then product quality increases, but production time extends and costs increase
Solution Approach 1:
The extraction, evaporation, and crystallization sections operate continuously in sequence, eliminating the time losses associated with batch processing between purification steps. This continuous flow through multiple purification stages achieves high product purity without extending overall production time.
Solution Approach 2:
Multiple purification functions (extraction, evaporation, crystallization) are merged into a single continuous production line where materials flow sequentially through each stage. This integration achieves comprehensive purification while maintaining continuous operation, avoiding the time penalties of separate batch purification processes.
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 LiFSI with low moisture content, suitable for industrial production, reducing production costs and waste generation, and enabling efficient recycling of raw materials.
Implementation Method 1
performing evaporation on the stream α1 to obtain a stream α2 containing (SO2F—NH—SO2F)·Et3N and the triethylamine hydrogen fluoride salt
Implementation Method 2
washing the stream α2 obtained in step (b) with water in an extraction tower or a static mixer to obtain an oil phase α3 containing (SO2F—NH—SO2F)·Et3N and an aqueous phase αwater containing the triethylamine hydrogen fluoride salt
Implementation Method 3
performing reduced-pressure evaporation on the stream β1-1 to obtain a stream β1-2 containing lithium bis(fluorosulfonyl)imide
Implementation Method 4
pumping the crude lithium bis(fluorosulfonyl)imide β3 obtained in step (f) to a crystallization kettle, and adding dichloromethane to precipitate lithium bis(fluorosulfonyl)imide crystals
Data Source
AI summary
The present application provides a method for preparing lithium bis(fluorosulfonyl)imide, which may include the following steps: (a) a synthesis step; (b) an evaporation step; (c) an extraction step; (d) an alkalinization step; (e) a dehydration step; (f) a desolventization step; (g) a crystallization step; and (h) a drying step; lithium bis(fluorosulfonyl)imide prepared by the method, an electrolytic solution containing the lithium bis(fluorosulfonyl)imide, and a secondary battery thereof.