Insights into the Redox Chemistry of Organosulfides Towards Stable Molecule Design in Nonaqueous Energy Storage Systems.

Nonaqueous redox flow batteries (RFBs) have great potential to achieve high-energy storage systems. However, they have been limited by low solubility and poor stability of active materials. Here we demonstrate organosulfides as a new-type model material system to explore the rational design of redox-active molecules in nonaqueous systems. The tetraethylthiuram disulfide (TETD) molecule shows high solubility in various common organic solvents and achieves a high reversible capacity of ca. 50 Ah L at a high concentration of 1 M. The resonance structures in the reduced product endow the molecule with high electrochemical stability in different organic electrolytes. The underlying mechanism in redox chemistry of organodisulfides involving the cleavage and reformation of disulfide bonds is revealed by material/structural characterizations. This study provides a new perspective of molecule designs for the development of redox-active materials for high-performance nonaqueous RFBs.