Bromine–Graphite Intercalation Enabled Two-Electron Transfer for a Bromine-Based Flow Battery

Abstract Br 2 /Br − is a promising redox couple in flow batteries because of its high potential, solubility, and low cost. However, the reaction between only involves single-electron transfer process, which limits energy density. Herein, novel two-electron based on + was studied realized through intercalation into graphite to form bromine–graphite compound (Br–GIC). Compared with pristine pair, potential intercalation/deintercalation 0.5 V higher, has substantially increase Different from electrolyte, diffusion rate decreases increasing charge state decreasing sites graphite, integrity structure important for reaction. As result, battery can continuously run more than 300 cycles Coulombic efficiency exceeding 97% an approximately 80% at 30 mA/cm , density increases by 65% compared . Combined double-electron highly reversible electrochemical demonstrates very prospects stationary storage.