High anodic stability of a new electrolyte solvent: Unsymmetric noncyclic aliphatic sulfone

To improve the anodic stability of ambient temperature electrolytes, a nontoxic solvent based on the sulfone polar group has been synthesized and evaluated in the presence of high potential cathode materials. Solutions of high stability salts such as LiClO₄ and Li imide in this solvent, withstand 5.8 V vs. Li⁺/Li before onset of oxidation, defined by a stringent criterion, even in the presence of high surface area electrodes such as activated charcoal on Pt. Reversible Li deposition and stripping is observed at negative potentials. This means not only that a wide range of overcharge protection is available for high voltage cathodes in current use, but also that exotic cathodes accepting electrons up to 5.5 V from Li⁺/Li may now be incorporated in rechargeable lithium cells.