Method for removing moisture and chloride ions in fluoroethylene carbonate

Abstract

The invention discloses a method for removing water and chloride ions in fluoroethylene carbonate, which comprises the following steps of: removing water by using an alkaline drying agent until the water content is less than or equal to 30ppm, so that no metal cation pollution is generated after the reaction, removing the chloride ions, and dynamically cooling and crystallizing, so that the obtained crystal is uniform in size and can be prevented from being adhered to the wall in a large area; the method is easy to operate in the subsequent filtering process, heating is not adopted in the whole water removal process, operation is easy and convenient, and the problems that a traditional heating distillation method is large in energy consumption, tedious in step, low in efficiency and high in water content are solved.

Description

Technical field: [0001] The invention relates to the technical field of purification, in particular to a method for removing moisture and chloride ions in fluoroethylene carbonate. Background technique: [0002] Fluoroethylene Carbonate (FEC) as a lithium battery electrolyte additive, not only can form a tight structure layer without increasing the electrolyte impedance, but also can prevent the electrolyte from further decomposition, has good high and low temperature performance and anti- Inflatable function. At the same time, it can also promote the formation of SEI film, improve the cycle performance of the battery, and improve the overall performance of the electrolyte. [0003] In order to obtain higher purity fluoroethylene carbonate, the industry usually adopts the method of multi-stage rectification to carry out purification. But this method has the following disadvantages: the first is that due to the high boiling point of fluoroethylene carbonate itself, the ener...

AI Technical Summary

Problems solved by technology

But this method has the following disadvantages: the first is that due to the high boiling point of fluoroethylene carbonate itself, the energy consumption of the multi-stage rectification method is very large, which is not conducive to the energy saving and emission reduction of enterprises; the second is that the residual moisture content is relatively high high

[0004] Most of the preparation methods about fluoroethylene carbonate reported at present are obtained by fluorination reaction between chloroethylene carbonate and potassium fluoride. This preparation method will inevitably cause obvious residual chloride ions in the product. Post-treatment Most of the purification methods used in purification are directly distilling the crude product, lacking a special process for removing chloride ions, which often leads to large fluctuations in the content of chloride ions in the product and unstable product quality

The residual amount of chloride ions is high, and the use in lithium-ion batteries will lead to a decline in the performance of lithium-ion batteries

[0005] CN106810527A discloses a preparation method of high-purity fluoroethylene carbonate. First, hydrotalcite adsorbent absorbs chloride ions, then adds molecular sieve, activated carbon, montmorillonite or activated alumina desiccant, and finally puts into internal circulation type thin film molecular distillation Molecular distillation is carried out in the equipment, but there are problems of cumbersome steps and high energy consumption