In the present invention, a bis (fluorosulfonyl) imide metal salt is an alkali metal salt of bis (fluorosulfonyl) imide or an alkaline earth metal salt of bis (fluorosulfonyl) imide. The bis (fluorosulfonyl) imide metal salt has an average particle diameter of not less than 0.1 mm, or has an average moisture absorption rate of not more than 2.5 mass ppm/cm.sup.2.Math.min when sealed in a PE bag having a thickness of 80 m and left for 30 minutes at 23 C. and 65% humidity.

In the present invention, a bis (fluorosulfonyl) imide metal salt is an alkali metal salt of bis (fluorosulfonyl) imide or an alkaline earth metal salt of bis (fluorosulfonyl) imide. The bis (fluorosulfonyl) imide metal salt has an average particle diameter of not less than 0.1 mm, or has an average moisture absorption rate of not more than 2.5 mass ppm/cm.sup.2.Math.min when sealed in a PE bag having a thickness of 80 m and left for 30 minutes at 23 C. and 65% humidity.

The invention relates to a method for the preparation of bis(fluorosulfonyl)-imide and its derivatives at elevated temperature.

The invention relates to a method for the preparation of bis(fluorosulfonyl)-imide and its derivatives at elevated temperature.

The present invention relates to an electrolyte additive comprising a salt of an anion with K.sup.+ or Na.sup.+, the anion being derived from a nitrogen atom-containing compound, and a lithium difluoro bis(oxalato)phosphate. In addition, the present invention provides a lithium salt, a non-aqueous organic solvent, and the electrolyte additive. The present invention relates to a lithium secondary battery which includes a cathode employing a cathode active material, an anode employing an anode active material, a separator interposed between the cathode and the anode, and the non-aqueous electrolyte.

The present invention relates to an electrolyte additive comprising a salt of an anion with K.sup.+ or Na.sup.+, the anion being derived from a nitrogen atom-containing compound, and a lithium difluoro bis(oxalato)phosphate. In addition, the present invention provides a lithium salt, a non-aqueous organic solvent, and the electrolyte additive. The present invention relates to a lithium secondary battery which includes a cathode employing a cathode active material, an anode employing an anode active material, a separator interposed between the cathode and the anode, and the non-aqueous electrolyte.

The present invention relates to an electrolyte additive comprising a salt of an anion with K.sup.+ or Na.sup.+, the anion being derived from a nitrogen atom-containing compound, and a lithium-containing compound for forming a coating film. In addition, the present invention provides a lithium salt, a non-aqueous organic solvent, and the electrolyte additive. The present invention relates to a lithium secondary battery which includes a cathode employing a cathode active material, an anode employing an anode active material, a separator interposed between the cathode and the anode, and the non-aqueous electrolyte.

The present invention relates to an electrolyte additive comprising a salt of an anion with K.sup.+ or Na.sup.+, the anion being derived from a nitrogen atom-containing compound, and a lithium-containing compound for forming a coating film. In addition, the present invention provides a lithium salt, a non-aqueous organic solvent, and the electrolyte additive. The present invention relates to a lithium secondary battery which includes a cathode employing a cathode active material, an anode employing an anode active material, a separator interposed between the cathode and the anode, and the non-aqueous electrolyte.

The present disclosure relates to a new method for producing alkali salt of bis(fluorosulfonyl)imide of high purity, as industrial scale, and with a reasonable cost when compared to the other available methods. Said method comprises the steps of reacting a bis(chlorosulfonyl)imide or a salt thereof with an onium chloride to produce an onium salt of bis(chlorosulfonyl)imide; reacting an onium salt of bis(chlorosulfonyl)imide with anhydrous hydrogen fluoride in at least one organic solvent to produce onium salt of bis(fluorosulfonyl)imide; and reacting the onium salt of bis(fluorosulfonyl)imide with an alkali salt to obtain alkali salt of bis(fluorosulfonyl)imide.

The present invention relates to bis(fluorosulfonyl)imide salts, and their preparation methods. More specifically, the invention provides a new salt of bis(fluorosulfonyl)imide containing from 0.01 ppm to 10000 ppm of a halogenated alcohol. The invention further relates to a method for producing said salt of bis(fluorosulfonyl)imide, said method comprising a step of crystallizing a raw salt of bis(fluorosulfonyl)imide within a crystallization solvent comprising at least a halogenated alcohol. The use of said salt of bis(fluorosulfonyl)imide is also disclosed.