Efficient Nitrogen-Doped Carbon for Zinc-Bromine Flow Battery.

The zinc-bromine flow battery (ZBFB) is one of the most promising technologies for large-scale energy storage. Here, nitrogen-doped carbon is synthesized and investigated as the positive electrode material in ZBFBs. The synthesis includes the carbonization of the glucose precursor and nitrogen doping by etching in ammonia gas. Physicochemical characterizations reveal that the resultant carbon exhibits high electronic conductivity, large specific surface area, and abundant heteroatom-containing functional groups, which benefit the formation and exposure of the active sites toward the Br2 /Br- redox couple. As a result, the assembled ZBFB achieves a voltage efficiency of 83.0% and an energy efficiency of 82.5% at a current density of 80 mA cm-2 , which are among the top values in literature. Finally, the ZBFB does not yield any detectable degradation in performance after a 200-cycle charging/discharging test, revealing its high stability. In summary, this work provides a highly efficient electrode material for the zinc-bromine flow battery.