Method for producing lithium hexafluorophosphate

Abstract

The invention relates to a method for producing lithium hexafluorophosphate. The method comprises the following steps: (1), rectifying and purifying industrial anhydrous hydrogen fluoride and removing moisture and heavy metal impurities therein; (2), enabling the rectified anhydrous hydrogen fluoride and phosphorus pentachloride to react to prepare the mixed gas of phosphorus pentafluoride and chlorine hydride; (3), dissolving high-pure lithium fluoride in an anhydrous hydrogen fluoride solution to form an anhydrous hydrogen fluoride solution containing the lithium fluoride; (4), cooling and guiding the mixed gas of the phosphorus pentafluoride and the chlorine hydride to 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 gas of the phosphorus pentafluoride and the chlorine hydride after a reaction to the other anhydrous hydrogen fluoride solution containing the lithium fluoride and continuously reacting to obtain a lithium hexafluorophosphate finished product. The invention uses the industrial anhydrous hydrogen fluoride, the phosphorus pentachloride and the high-pure lithium fluoride as raw materials to prepare the lithium hexafluorophosphate product, has rich raw material resources, low production cost, high reaction rate, high product quality and thorough reaction and can realize semi-continuous production.

Description

technical field [0001] The invention relates to a method for producing lithium hexafluorophosphate, belonging to the technical field of lithium ion batteries. 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 batteries are internationally recognized as ideal chemical energy sources. They are small in size, large in capacity, can be charged and discharged 500 times, and their capacity is only reduced by 3%. They are widely used in mobile phones, laptop computers, and camcorders. It is used as a dopant for making wafers in the electronics industry and as a catalyst for organic synthesis. Currently, because of the preparation of lithium hexafluorophosphate (LiPF 6 ) has many production links, complex process a...

AI Technical Summary

Problems solved by technology

Currently, because of the preparation of lithium hexafluorophosphate (LiPF 6 ) has many production links, complicated process and high equipment requirements, so the production cost remains high

[0003] Japanese Patent Application Publication No. Ping 5-279003 discloses a method for preparing lithium hexafluorophosphate, which comprises reacting phosphorus pentachloride with hydrogen fluoride gas to generate phosphorus pentafluoride and hydrogen chloride gas, and then making the resulting phosphorus pentafluoride and hydrogen chloride The gas passes through a cooling tower with a tower temperature of -40 to -80°C, and then enters a reactor containing a hydrofluoric acid solution of lithium fluoride to prepare lithium hexafluorophosphate. The disadvantage of this method is that the reaction yield does not exceed 65%.

[0004] The Chinese Patent Gazette discloses an application for an invention patent with the application number: 200610013957.5, and its name is: the method for preparing lithium hexafluorophosphate. Phosphorus pentachloride reacts with anhydrous hydrogen fluoride solution to prepare a mixed gas of phosphorus pentafluoride and hydrogen chloride, then introduces the mixed gas of phosphorus pentafluoride and hydrogen chloride into anhydrous hydrogen fluoride solution of lithium fluoride, reacts, crystallizes, separates, and dries The pure lithium hexafluorophosphate product is obtained, the disadvantage of this method is that the continuity is not good enough