Oxygen-enriched electrolytes based on perfluorochemicals for high-capacity lithium–oxygen batteries

Abstract

Electrolytes highly enriched with oxygen for lithium–oxygen (Li–O₂) batteries were prepared by combining perfluorohexyl bromide as an oxygen-uptake perfluorochemical (PFC) medium with lithium perfluorooctane sulfonate (LiPFOS) as a perfluoro-surfactant and a supporting electrolyte, which allowed an exceptionally high miscibility of PFCs with tetraethylene glycol dimethyl ether (TEGDME). The electrochemical reduction current of oxygen was enhanced three times in the LiPFOS–TEGDME electrolyte with ca. 60 wt% PFC content in comparison with that of a conventional Li–O₂ battery electrolyte, which was ascribed to the high oxygen solubility of the electrolyte. A Li–O₂ cell fabricated with the PFC-based electrolyte exhibited an excellent discharging capacity of 6500 mA h g⁻¹ which was approximately 1.5 times higher than that obtained with the conventional electrolyte.