High conductivity molten salts based on the imide ion

The bis(trifluoromethanesulfonyl)imide ion has recently been used in its li thium salt as a useful ion in solid polymer electrolytes because of the red uced degree of ion interaction its diffuse charge generates. In this work w e have synthesised a number of novel salts based on the ammonium and pyrrol idinium cations of this anion. The salts all show reduced melting points co mpared with analogous halide salts. In some cases they are molten at room t emperature. This latter group of salts have been characterized with respect to their properties as ionic liquids; the highest room temperature conduct ivity 2 mS cm(-1) being exhibited by methyl butyl pyrrolidinium imide. Many of the salts are glass forming, exhibiting glass transition temperatures i n the region of -90 degrees C. (C) 2000 Elsevier Science Ltd. All rights re served.