A bipolar nitronyl nitroxide small molecule for an all-organic symmetric redox-flow battery

A compound that can replace corrosive metal salts in fuel-cell-like ‘flow’ batteries has been discovered by a team in Germany. Redox flow batteries produce electrochemical energy by moving an electrolyte between separated cathode and anode compartments. These devices, which can be recharged nearly instantly by replacing the electrolyte, are set to become more sustainable thanks to a chemical synthesis developed by Ulrich S. Schubert from Friedrich Schiller University and colleagues. The team designed an organic molecule capable of acting as both battery anode and cathode through aromatic nitronyl nitroxide groups that release or take in electrons at moderate voltages. Attaching the aromatic redox units to a glycol chain gave the compound the solubility needed to make a flow battery with better capacity and efficiency than previous all-organic attempts.