Modified Tetrathiafulvalene as an Organic Conductor for Improving Performances of Li-O2 Batteries.

Large over-potentials owing to the sluggish kinetics of battery reactions have always been the drawbacks of Li-O2 batteries, which lead to short cycle life. Although redox mediators have been intensively investigated to overcome this issue, side-reactions are generally induced by the solvated nature of redox mediators. Herein, we report an alternative method to achieve more efficient utilization of tetrathiafulvalene (TTF) in Li-O2 batteries. By coordinating TTF+ with LiCl during charging, an organic conductor TTF+ Clx- precipitate covers Li2 O2 to provide an additional electron-transfer pathway on the surface, which can significantly reduce the charge over-potential, improve the energy efficiency of Li-O2 batteries, and eliminate side-reactions between the lithium metal anode and TTF+ . When a porous graphene electrode is used, the Li-O2 battery combined with TTF and LiCl shows an outstanding performance and prolonged cycle life.