Electrochemical energy storage systems and methods featuring high open circuit potential

Abstract

The invention concerns flow batteries comprising: a first aqueous electrolyte comprising a first redox active material; a second aqueous electrolyte comprising a second redox active material; a first electrode in contact with the first aqueous electrolyte; a second electrode in contact with the second aqueous electrolyte and a separator disposed between the first aqueous electrolyte and the second aqueous electrolyte; the flow battery having an open circuit potential of at least 1.4 V, and is capable of operating or is operating at a current density at least about 50 mA/cm, wherein both of the first and second redox active materials remain soluble in both the charged and discharged states. In certain embodiments, the redox active materials are metal ligand coordination compounds. The disclosure also describes systems comprising these flow batteries and methods of them.