Lithium difluoro-bis(oxalate)phosphate, preparation method therefor, and application thereof
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Solution Overview
Problem
Current methods for preparing lithium difluorobis(oxalato)phosphate in lithium-ion batteries face challenges such as low safety, poor reliability, and high industrialization difficulties due to the production of corrosive gases and complex post-treatment processes, which hinder industrial production.
Innovation Solution
A method involving the reaction of oxalyl chloride and lithium hexafluorophosphate with hexamethyldisiloxane in a nonaqueous solvent, followed by crystallization, to produce lithium difluorobis(oxalato)phosphate with high purity and reduced impurities, using a controlled molar ratio and inert atmosphere to minimize side reactions and waste production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium hexafluorophosphate and silicon tetrachloride are used as raw materials to prepare lithium difluorobis(oxalato)phosphate, then the product can be obtained, but phosphorus pentafluoride is produced as a harmful byproduct that is difficult to remove
Solution Approach 1:
The patent extracts and removes the harmful phosphorus pentafluoride byproduct through a specific purification process involving treatment with lithium hydroxide solution, separating it from the desired lithium difluorobis(oxalato)phosphate product to achieve high purity
Solution Approach 2:
The patent introduces lithium hydroxide solution as an intermediary substance to react with and neutralize the phosphorus pentafluoride impurity, converting it into removable salts and enabling effective purification of the final product
2Quantity of substance
If silicon-based auxiliaries are used in the reaction process, then lithium difluorobis(oxalato)phosphate can be prepared, but a large amount of silicon tetrafluoride and hydrogen chloride gas are produced which are difficult to separate and pose safety risks
Solution Approach 1:
The patent converts the harmful silicon tetrafluoride and hydrogen chloride gases into beneficial or manageable substances by reacting them with lithium hydroxide solution, transforming the hazardous byproducts into soluble salts that can be easily removed through filtration and evaporation
Solution Approach 2:
The patent employs an inert atmosphere (nitrogen or argon) during the reaction process to prevent unwanted side reactions and to safely contain and manage the corrosive gases produced, reducing safety risks and improving process control
3Quantity of substance
If hexafluorophosphoric acid, lithium oxalate and silicon tetrachloride are used as raw materials, then lithium difluorobis(oxalato)phosphate can be prepared, but highly corrosive acid gases are produced that have very high requirements for equipment and are difficult to separate
Solution Approach 1:
The patent extracts the corrosive acid gases from the reaction system by introducing lithium hydroxide solution that absorbs and neutralizes these gases, allowing them to be removed through simple filtration and evaporation processes rather than requiring complex separation equipment
Solution Approach 2:
The patent uses lithium hydroxide solution as a disposable reagent that easily neutralizes and removes the corrosive gases, eliminating the need for expensive specialized equipment designed to handle highly corrosive environments
4Quantity of substance
If silazane is used as a reagent to prepare lithium difluorobis(oxalato)phosphate, then the product can be obtained, but ammonia gas and fluorosilane are produced that are difficult to separate and complicate post-treatment
Solution Approach 1:
The patent extracts and removes the difficult-to-separate ammonia gas and fluorosilane byproducts through treatment with lithium hydroxide solution, which converts them into water-soluble salts that can be easily separated from the organic product phase through simple filtration and evaporation
Solution Approach 2:
The patent changes the chemical state of the problematic byproducts by adjusting the pH and chemical environment through lithium hydroxide addition, transforming ammonia and fluorosilane into ionic forms that are easily separable, thereby simplifying the post-treatment process
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 achieves high product purity and yield, reduces the risk of corrosive gas production, and simplifies the process, making it safer and more suitable for industrial production with fewer impurities and lower costs.
Implementation Method 1
mixing oxalyl chloride and lithium hexafluorophosphate with a nonaqueous solvent, adding siloxane, and reacting to obtain a lithium difluorobis(oxalato)phosphate solution
Implementation Method 2
adding a poor solvent into the lithium difluorobis(oxalato)phosphate solution for crystallization to obtain the lithium difluorobis(oxalato)phosphate
Data Source
AI summary
Disclosed are lithium difluoro-bis(oxalate)phosphate, a preparation method therefor, and an application thereof. The preparation method comprises the following steps: (1) mixing oxalyl chloride and lithium hexafluorophosphate with a nonaqueous solvent, adding siloxane, and reacting to obtain a lithium difluoro-bis(oxalate)phosphate solution; and (2) adding a poor solvent into the lithium difluoro-bis(oxalate)phosphate solution for crystallization treatment to obtain the lithium difluoro-bis(oxalate)phosphate. According to the present application, raw materials such as lithium hexafluorophosphate, oxalyl chloride, and hexamethyldisiloxane are used for preparing the difluoro-bis(oxalate)phosphate, and the method of the present application is few in side reaction, few in impurities, high in product purity, and suitable for industrial production.