NOVEL ONIUM SALT, ELECTROLYTE FOR NONAQUEOUS CELL CONTAINING THE NOVEL ONIUM SALT FOR NONAQUEOUS CELL, AND METHOD FOR OPTIMIZING NEGATIVE ELECTRODE USING ELECTROLYTE CONTAINING ONIUM SALT

摘要

A novel onium salt; and a method for optimizing the interface of a negative electrode by the use of the novel onium salt or the novel onium salt and a conventional onium salt, characterized in that it comprises causing an electrolyte containing novel tetraethylammonium 2,2,2−trifluoro−N−(trifluoromethanesulfonyl)acetamide to be present between a negative electrode and a positive electrode in an electrochemical device having the constitution : negative electrode ‖ electrolyte ‖ positive electrode, to thereby construct an electrode structure in an electrochemical device, and applying a voltage between the negative electrode and the positive electrode so as for the negative electrode to have a potential of −1 V to −5 V in terms of the potential relative to a reference electrode of I−/I3−, to thereby form a passivating layer comprising a decomposition product of the above electrolyte or salt on the surface of the above negative electrode.