| Abstract: | The fundamental charge storage mechanisms in a number of currently
studied high energy redox couples are based on intercalation, conversion,
or displacement reactions. With exception to certain metal-air
chemistries, most often the active redox materials are stored physically
in the electrochemical cell stack thereby lowering the practical
gravimetric and volumetric energy density as a tradeoff to achieve
reasonable power density. In a general embodiment, a mediated redox flow
battery includes a series of secondary organic molecules that form highly
reduced anionic radicals as reaction mediator pairs for the reduction and
oxidation of primary high capacity redox species ex situ from the
electrochemical cell stack. Arenes are reduced to stable anionic radicals
that in turn reduce a primary anode to the charged state. The primary
anode is then discharged using a second lower potential (more positive)
arene. Compatible separators and solvents are also disclosed herein. |