Method for preparing potassium hexafluoro phosphate

Abstract

The invention relates to Li ion battery technique, a lithium hexafluoro- phosphate preparing method, characterized in comprising the process steps of: using easy sublimation property of phosphorus pentachloride, heating and sublimating it to remove nonvolatile components, refining industrial anhydrous hydrogen fluoride to remove water and heavy metal impurities; reacting them with each other to prepare mixed gas of phosphorus pentachloride and hydrogen chloride; leading the mixed gas into anhydrous hydrogen fluoride of lithium fluoride, reacting, crystallizing and separating and drying to obtain pure lithium hexafluoro-phosphate.

Description

technical field [0001] The present invention relates to lithium ion battery technology, specifically a preparation method of lithium hexafluorophosphate. Background technique [0002] Lithium hexafluorophosphate is an important electrolyte salt of lithium-ion battery electrolyte. The preparation method of lithium hexafluorophosphate generally includes two methods. [0003] The first method is to prepare PF by reacting red phosphorus and fluorine gas 5 gas, then react with anhydrous hydrogen fluoride solution of lithium fluoride, crystallize, separate and dry to obtain lithium hexafluorophosphate product. Such as JP-A-2001-122604; 122605; 163610. [0004] The second method is to react phosphorus pentachloride with anhydrous hydrogen fluoride to generate a mixed gas of phosphorus pentafluoride and hydrogen chloride, then react with anhydrous hydrogen fluoride solution of lithium fluoride, and obtain lithium hexafluorophosphate product through reaction, crystallization, sepa...

AI Technical Summary

Problems solved by technology

[0005] During the preparation of lithium hexafluorophosphate, the raw materials such as phosphorus pentachloride, anhydrous hydrogen fluoride, and lithium fluoride usually contain certain impurities such as water, alkali metals, and heavy metal ions, especially phosphorus pentachloride, which is easy to absorb moisture and produces deliquescence. , the product contains PCl 3 , POCl 3 If the above-mentioned impurities are brought into the lithium hexafluorophosphate product, and the product is prepared into an electrolyte and used in a lithium-ion battery, it will cause an increase in the internal resistance of the battery, a rapid decay of the battery capacity, a shortened cycle life, and even affect the safety of the battery.

but using F 2 , not only has high toxicity, but also is more expensive, which will increase the manufacturing cost of the product

[0018] Lithium hexafluorophosphate is recrystallized in an organic solvent, taking advantage of its different solubility properties at different temperatures, but a certain amount of organic solvent will still be entrained in the recrystallized product, which will affect the purity of the product

[0019] PF can be removed by cooling at lower temperature 5 and POF in HCl gas 3 impurities but cannot effectively remove other harmful impurities, and the cost is higher