Synthesis method for bis(fluorosulfonyl)imide salt

The invention discloses a synthesis method for a bis(fluorosulfonyl)imide salt, wherein the method comprises the following steps: (one) under the protection of nitrogen, dissolving a bis(chlorosulfonyl)imide salt in a nonprotic organic solvent to obtain a bis(chlorosulfonyl)imide salt organic solution; (two) under a stirring condition, adding an excess compound fluridizer into the organic solution, then heating to a temperature being 8 DEG C-20 DEG C higher than an organic solvent boiling point temperature, and making the bis(chlorosulfonyl)imide salt to undergo an effective fluorination reaction in the organic solvent, wherein the compound fluridizer is selected from at least two substances of antimony trifluoride, potassium fluoride, zinc fluoride and aluminum fluoride; (three) after the reaction is finished, filtering the reaction liquid, and concentrating the filtrate to obtain a concentrated solution; and (four) crystallizing the concentrated solution, filtering, drying, and thus obtaining the high-purity bis(fluorosulfonyl)imide salt. The synthesis method has the advantages of simple operation, high product productive rate, no toxic reagent to pollute the environment, and high purity of the product, and is suitable for large-scale production in industry.