Polythianthrene ladder oligomers function as an organic battery electrode with a high oxidation potential

We report the electrochemical characterization of a polythianthrene ladder polymer as a promising positive electrode active material for organic polymer batteries. Polythianthrene was synthesized as a distribution of relatively short oligomers (n = 3 to ∼20) by the condensation of diphenylsulfide catalyzed by AlCl3, and its likely solid-state structure was determined by molecular modeling in combination with X-ray powder diffraction. Polythianthrene functions as the active material in an anion-insertion positive battery electrode with a highly positive potential of +0.87 V vs. ferrocene+/0, or approximately 4.1 V vs. Li/Li+. It has a specific capacity of 71 mAh/g, which may be improved toward a theoretical capacity of 194 mAh/g for one-electron redox per repeat unit. The polythianthrene ladder polymer thus has both a high capacity and high voltage relative to other organic materials, and is a promising material for use as a positive electrode in a “dual-ion” battery.