A highly selective porous composite membrane with bromine capturing ability for a bromine-based flow battery

Bromine-based flow batteries (Br-FBs) are receiving more and attention because of the high potential, solubility, low cost Br2/Br− redox couple. However, self-discharge reaction caused by bromine diffusion leads to serious irreversible capacity decay Br-FBs. Herein, a porous composite membrane is designed for Br-FBs, upon which highly selective separation layer constructed introducing complexing agent. Apart from intrinsically selectivity on bromine, agent in non-porous can complex with diffused bromine. Therefore, captured layer, consequently suppressing self-discharging battery. The zinc–bromine single battery (ZBSFB) assembled prepared demonstrates Coulombic efficiency 97.42% an energy 85.31% at 40 mA/cm2. Moreover, this operate stably current density 140 mA/cm2, much higher than that pristine matrix (only mA/cm2), enabling higher-power ZBSFB. Most importantly, ZBSFB exhibits retention rate after resting 24 h based (69.3% vs. 35.7%), suggesting dramatically improved selectivity. membranes be very promising prospect Br-FB applications.