A high-rate nonaqueous organic redox flow battery

Azobenzene (azoB) is a promising anode active material for nonaqueous redox flow battery (NARFB), but the battery performance assembled with azoB is rather poor. Here, we show that the rate performance of NARFB with azoB and 2,5-di-tert-butyl-1-methoxy-4-[2?-methoxyethoxy] benzene (DBMMB) as anolyte and catholyte active materials can be significantly enhanced by optimizing the solvent, supporting electrolyte, and membrane. The synergistic interaction among active materials, solvent (acetonitrile), supporting electrolyte (tetraethylammonium bis(trifluoromethylsulfonyl)imide), and membrane (Daramic 175) contributes to the high battery performance. It exhibits an energy efficiency of 63.5% even at an ultra-high current density of 100 mA cm-2. Furthermore, the battery delivers a peak power density of 336 mW cm-2 at the current density of 240 mA cm-2 with 0.25 M active materials, which is a new benchmark for NARFBs.

Automated summary

The use of azoB as anode active material in NARFB shows promise but poor performance, which can be significantly enhanced through optimization of solvent, supporting electrolyte, and membrane. The synergistic interaction among active materials, solvent, supporting electrolyte, and membrane contributes to the high battery performance, achieving a new benchmark for NARFBs.