Sulfone-based electrolytes for lithium-ion batteries

A series of cyclic or acyclic sulfones have been synthesized and evaluated as electrolyte solvents for lithium (ion) batteries. This report summarizes the physical and electrochemical properties of these new compounds. It is found that, while the anodic stability of these solvents is independent of the sulfone structure, i.e., no oxidative decomposition is observed before 5.5 V vs. Li in any sulfone, the structure of their alkyl substituents dictates their compatibility with graphitic anodes. In the most favorable cases, this compatibility is comparable with that found with carbonate-based electrolytes. Fluorination of alkyl groups in the sulfone seems to help in forming a stable solid electrolyte interface on the anode, while also improving the conductivity. Initial tests of these cells containing such electrolyte solvents show promising performance. (C) 2002 The Electrochemical Society.