Novel weakly coordinating heterocyclic anions for use in lithium batteries

Ab initio calculations have been performed for a new family of lithium salts based on heterocyclic anions: [CF3SON4C2n](-) (0 <= n <= 4). In total, 10 different anions and their 1:1 ion pairs with lithium ions have been studied. The lithium ion affinity globally decreases with the degree of CN-substitution to the ring. Bidentate lithium ion coordination to the sulfonyl oxygen atom and one additional atom or to two adjacent ring nitrogen atoms is strongly preferred when structurally possible. The extremely low lithium ion affinities of the anions together with an appreciable stability towards oxidation make these salts possible candidates for future lithium battery electrolytes. (C) 2007 Elsevier B.V. All rights reserved.