Preparation method of lithium hexafluorophosphate

Abstract

The invention relates to a preparation method of lithium hexafluorophosphate. The method comprises the following steps: (1), enabling anhydrous hydrogen fluoride and strong phosphoric acid to react under the protection of inert gas to prepare hexafluorophosphoric acid; (2), adding oleum to the hexafluorophosphoric acid prepared in the step (1) under cooling stirring to prepare phosphorus pentafluoride gas; (3), dissolving high-purity lithium fluoride in an anhydrous hydrogen fluoride solution to form an anhydrous hydrogen fluoride solution containing the lithium fluoride; (4), cooling and guiding the phosphorus pentafluoride gas into the anhydrous hydrogen fluoride solution containing the lithium fluoride, reacting, crystallizing, separating and drying to obtain a pure lithium hexafluorophosphate product; and (5), continuously guiding the unreacted and cooled phosphorus pentafluoride gas to the anhydrous hydrogen fluoride solution containing the lithium fluoride and continuously reacting to obtain a lithium hexafluorophosphate finished product. The phosphorus pentafluoride in the process is cooled to fully react so as to prevent incomplete reacted phosphorus pentafluoride powder from causing environmental-protection pressure.

Description

technical field [0001] The invention relates to a preparation method of lithium hexafluorophosphate. Background technique [0002] In recent years, lithium hexafluorophosphate (LiPF 6 ) is selected as the electrolyte of the lithium-ion secondary battery, and lithium hexafluorophosphate is dissolved in some non-aqueous organic solvents to form the electrolyte of the lithium-ion secondary battery. Lithium-ion secondary battery is an internationally recognized ideal chemical energy source. It is widely used in mobile phones, laptop computers and laptops due to its advantages of small size, large capacity, 500 times of repeated charge and discharge, and only 3% reduction in capacity. Video cameras, etc., are also used in the electronics industry as a dopant for making wafers and as a catalyst for organic synthesis. When the lithium-ion secondary battery is charged, lithium ions enter and attach to the hole in the cathode; while the lithium-ion secondary battery is discharged, ...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the cost of raw materials is high and the continuity of equipment operation is not good enough

[0005] The Chinese Patent Gazette also discloses an invention patent application with the application number: 200510115856.4, and the invention name is: a preparation method of lithium hexafluorophosphate, which includes reacting lithium fluoride with a phosphorus source, wherein the lithium fluoride is composed of lithium carbonate and It is produced by the reaction of hydrogen fluoride. The purity of lithium hexafluorophosphate produced by this method is relatively low and it is not easy to purify