The invention discloses a preparation method for
lithium bis(fluorosulfonyl)
imide. The preparation method comprises the following steps: 1) preparing
fluorine sulfamide lithium; 2) preparing
sulfuryl fluoride, and pumping the
sulfuryl fluoride into the
fluorine sulfamide lithium solution, and adding an acid-binding agent to prepare bifluorine sulfimide
ammonium salt; 3) dissolving the bifluorine sulfimide
ammonium salt in water solution, to obtain bifluorine sulfimide water solution through the acid resin exchange; 4) adding
lithium carbonate, regulating the PH value to be neutral, filtering and removing undissolved substances, depressurizing and removing the most of the water, and adding a weak-polarity
organic solvent to separate out a coarse product of the lithium bis(fluorosulfonyl)
imide, further depressurizing and
drying; and 5) adding a polarity
solvent to the coarse product of the lithium bis(fluorosulfonyl)
imide, stirring and dissolving, filtering and removing the undissolved substances, depressurizing and removing a strong-polarity
solvent, and adding the weak-polarity
organic solvent to perform the recrystallization, and depressurizing and
drying to obtain a product after filtering. The preparation method is simple, the reaction time is short, the yield is high, and
metal ion and negative
ion impurities can be effectively controlled, so that the product with the high purity can be obtained.