Preparation method of LiFSI (lithium bis(fluorosulfonyl)imide)

Abstract

The invention discloses a preparation method of LiFSI (imidodisulfuryl fluoride lithium salt). The method comprises steps as follows: S01, HFSI (lithium fluorosulfonimide) and organic lithium salt LiR are subjected to an exchange reaction under the solvent-free condition or an organic solvent condition to produce LiFSI and organic matter HR, wherein the PKa of the organic matter HR is 0-50, the exchange reaction is performed under the condition of gas protection, and the reaction temperature is 0-60 DEG C; S02: a reactant under the solvent-free condition in S01 is added to a poor reagent to be crystallized, and LiFSI is obtained after solid-liquid separation; S03: a reactant under the organic solvent condition in S01 is subjected to solid-liquid separation, a liquid phase is concentrated, the reactant is added to a poor reagent to be crystallized, and LiFSI is obtained after solid-liquid separation. The preparation method has the characteristics of simple steps, high yield, high purity, good stability and low impurity content.

Description

technical field [0001] The invention relates to a preparation method of bisfluorosulfonimide lithium salt, which belongs to the technical field of chemical synthesis. Background technique [0002] Lithium bisfluorosulfonyl imide, referred to as LiFSI, is a lithium salt electrolyte material that can be widely used. It has the characteristics of electrochemical stability and thermal stability in the electrolyte, and it will not produce corrosive substances such as hydrofluoric acid during use. The gas can improve the high and low temperature resistance of the SEI layer at the electrode interface at low temperatures, reduce the capacity loss of the lithium battery during placement, and improve battery performance. The patent US7709175 studies the electrical properties of LiFSI and finds that its properties are far superior to those of the current commercial lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4) and lithium bistrifluoromethanesulfonimide (LiTFSI)...

AI Technical Summary

Problems solved by technology

The problem that the method that this patent reports exists is that product purity and yield are too low, raw material consumption and waste generation are too much, and manufacturing cost is too high

[0009] From the analysis of the above-mentioned LiFSI production process, it is inevitable that there will be a problem of reaching equilibrium in the exchange reaction between MSFI and lithium salt, resulting in difficulty in purification and pollution of other metal ion impurities.

The use of HFSI as the starting material can avoid the pollution of other metal ion impurities. The solid-liquid two-phase reaction process releases a large amount of hydrochloric acid and is slow, which is easy to cause residual chloride ions; It cannot be effectively controlled, resulting in poor product quality. These various deficiencies also make it difficult for LiFSI to meet the quality requirements, and cannot make it suitable for industrial lithium battery applications.