Bromine-based flow batteries store energy using a chemical reaction between bromide ions and elemental bromine. This chemistry is attractive because bromine is widely available, has a high electrochemical potential, and dissolves well in liquid electrolytes. The downside appears during charging, when large amounts of bromine are produced. This reactive material can attack battery components, reduce how many charge cycles the battery can handle, and raise overall system costs. Additives known as bromine complexing agents can help limit corrosion, but they often cause the electrolyte to separate into different phases, which disrupts uniformity and makes the system harder to manage.
In a study published in Nature Energy, researchers led by Prof. Xianfeng Li from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) reported a new approach to bromine-based battery chemistry. The team designed a bromine-related reaction that transfers two electrons instead of one and successfully applied it to a zinc-bromine flow battery. Their results show both a working proof of concept and successful scale-up toward a long-life battery system.
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