Preparation method of hexafluorophosphoric acid alkali metal salt

Abstract

The invention belongs to the technical field of chemical synthesis, in particular to a preparation method of a hexafluorophosphoric acid alkali metal salt. The preparation method comprises the following steps: metering and introducing phosphorus pentafluorine gas and a fluorinated alkali metal salt solution into a microchannel reactor, mixing the phosphorus pentafluorine gas and the fluorinated alkali metal salt solution, carrying out reaction on a mixture, and carrying out crystallization and drying on an obtained reaction solution to obtain the hexafluorophosphoric acid alkali metal salt. According to the preparation method, a continuous flow microchannel reaction technology is adopted to synthesize the high-purity hexafluorophosphoric acid alkali metal salt, so that the reaction time is shortened to dozens of seconds or a few minutes from a few hours, the efficiency is remarkably improved, requirement for additionally configuring a device caused in the conventional intermittent reaction and leakages caused during transferring are prevented, and the safety is improved.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing an efficient alkali metal hexafluorophosphate. Background technique [0002] At present, most of the battery electrolyte materials demanded by the Chinese market are produced domestically, but most of the electrolyte required for production still relies on imports from Japan and South Korea. The lithium-ion battery electrolyte mainly includes organic solvents and electrolytes. The electrolyte used must have high conductivity, good chemical and electrochemical stability, a wide usable temperature range, and good safety. Alkali metal hexafluorophosphate is a commonly used electrolyte for lithium-ion secondary battery electrolytes. At present, due to the many production steps of alkali metal hexafluorophosphate, complex processes and high equipment requirements, the production cost remains high. [0003] The traditional preparation meth...

AI Technical Summary

Problems solved by technology

Alkali metal hexafluorophosphate is a commonly used electrolyte for lithium-ion secondary battery electrolytes. At present, due to the many production links of alkali metal hexafluorophosphate, complex processes and high equipment requirements, the production cost remains high.

[0003] The traditional preparation method of alkali metal hexafluorophosphate electrolyte is the organic solvent method. This method successively undergoes steps such as crystallization, separation, solvent removal, recrystallization, and vacuum drying. The production process is complicated, the purification is difficult, and the drying and desolventization are difficult. The obtained alkali metal hexafluorophosphate has low purity and low quality

[0004] Chinese patent CN1210810 discloses a tower reaction synthesis method of lithium hexafluorophosphate. The tower equipment of this process is placed vertically, so that the residence time of the reactants in the equipment is relatively short, and the mixing effect of the vapor-liquid reactants is poor.

Chinese patent CN102502566 discloses a synthesis process of lithium hexafluorophosphate. Lithium fluoride, anhydrous hydrogen fluoride, and phosphorus pentafluoride gas are reacted in a synthesis kettle to prepare lithium hexafluorophosphate, but continuous production cannot be carried out.

Chinese patent CN102976303 also completes the reaction process of anhydrous phosphorus source and fluoride in the reactor, and it takes a long time to prepare lithium hexafluorophosphate, and the output of a single reactor is not high

Chinese patent CN104555958 discloses a process for synthesizing lithium hexafluorophosphate by kettle reaction. Phosphorus pentafluoride gas is further reacted and absorbed with lithium fluoride anhydrous hydrogen fluoride solution in the kettle. reaction, the reaction conversion rate is low

Chinese patent CN101544361 discloses a continuous preparation process for synthesizing lithium hexafluorophosphate using multi-stage tubular reactors, which can realize continuous production, but the overall device is relatively complicated