A kind of preparation method of lithium hexafluorophosphate

Abstract

The invention provides a preparation method of high-purity and low-cost lithium hexafluorophosphate. The steps are as follows: (1) Add a sufficient amount of anhydrous hydrogen fluoride to the dry reactor, and make the hydrogen fluoride liquid under the action of the coolant; (2) pass the phosphorus pentafluoride gas generated by the reaction of calcium fluoride and phosphorus pentoxide through molecular sieves Adsorption and drying to remove impurities, and then introducing into the liquid formed in step (1) to form a hydrogen fluoride solution of hexafluorophosphoric acid; (3) slowly adding the hydrogen fluoride solution of high-purity lithium chloride to the solution formed in step (2), Reaction while stirring; (4) crystallization by lowering the temperature, passing dry phosphorus pentafluoride gas to react with entrained lithium fluoride and lithium oxyphosphate impurities to convert them into products. Heat up, absorb HF under reduced pressure with a vacuum absorber, and dry the product in vacuum to obtain high-purity lithium hexafluorophosphate with a purity of 99.96-99.99%. The present invention uses cheap and easy-to-obtain raw materials such as calcium fluoride, phosphorus pentoxide, and lithium chloride for the first time to synthesize lithium hexafluorophosphate through liquid-liquid reaction, preparation, separation, and purification in one pot. The production cost is low, the toxicity is small, the operation is simple, and the reaction rate is high. It is easy to control, simple to separate and remove impurities, high in product purity, and convenient for industrialization.

Description

technical field [0001] The invention relates to a preparation method of high-purity electrolyte lithium salt, in particular to a preparation method of high-purity and low-cost lithium hexafluorophosphate. Background technique [0002] Lithium hexafluorophosphate (LiPF 6 ) is currently the most widely used main electrolyte lithium salt in commercial lithium-ion batteries. With the promotion of new energy vehicles and the increase in demand for portable electronic products, the demand for electrolytes brought about by the doubling of the demand for lithium-ion batteries will show explosive growth. The current global electrolyte (LiPF 6 ) production is basically monopolized by three Japanese manufacturers (Morita Chemical, Kanto Denka, SUTERAKEMIFA), and Tianjin Jinniu Power Material Co., Ltd., the only industrialized company in China, only has a production capacity of 250 tons per year. Based on the current situation, it is imminent to carry out domestic research on lithium...

AI Technical Summary

Problems solved by technology

However, the cost of raw materials used in the anhydrous hydrogen fluoride solvent method that can be industrialized at present is relatively high, such as lithium fluoride; the synthesis conditions of high-purity phosphorus pentafluoride raw materials are harsh, and it is difficult to synthesize phosphorus pentafluoride with phosphorus pentachloride and hydrogen fluoride as raw materials. control, poor security

Using phosphorus pentoxide and hydrogen fluoride as raw materials to synthesize phosphorus pentafluoride has high impurity content, and the purity of raw materials and products is not enough, so it is difficult to meet the requirements of lithium-ion battery electrolytes; x f y Impurities are difficult to separate from the product lithium hexafluorophosphate