China's zinc–bromine battery runs 700 cycles with minimal corrosion

Chinese scientists led by Professor LI Xianfeng at the Dalian Institute of Chemical Physics have developed a novel bromine-based two-electron transfer reaction system that significantly improves zinc–bromine flow battery performance. This innovation addresses a major challenge in bromine-based flow batteries: the accumulation of corrosive elemental bromine (Br2) during charging, which typically accelerates component degradation and shortens battery life. By introducing amine compounds as bromine scavengers into the electrolyte, the researchers converted free bromine into brominated amine compounds, maintaining bromine concentrations at an ultra-low level (around 7 mM). This approach reduces electrolyte corrosivity and enhances battery stability and energy density. Applying this reaction system in a zinc–bromine flow battery enabled the use of a standard, non-fluorinated ion-exchange membrane, significantly lowering costs by avoiding expensive corrosion-resistant materials. The battery demonstrated stable operation for over 700 cycles at a current density of 40 mA/cm²