Rechargeable Li//Br battery: A promising platform for post lithium ion batteries

A rechargeable lithium battery, Li//Br, is reported using an aqueous bromide/tribromide redox pair and a coated lithium metal as the positive and negative electrodes, respectively. The positive Br₂ electrode shows fast redox kinetics and good stability. This battery presents excellent electrochemical performance with an average discharge voltage up to 3.96 V at 1.7 mA cm^-2, an energy density of 1220 Wh kg^-1, a power density of 29.7 mW cm^-2 at a current density of 12.8 mA cm^-2, and a long cycling life. There is no evidence of voltage decrease after 100 cycles at 35% DOD. It would become a good platform between lithium ion batteries and Li//air batteries since the former shows lower energy density and the latter has some challenging problems that need to be solved prior to practical application. This finding presents another promising choice for electrochemical energy storage systems.