A complete summary of viologen-based aqueous organic redox flow batteries is provided from materials synthesis to physicochemical properties and battery performance on the basis of conventional, π-conjugated extended, and polymeric viologens.
Viologens, a class of redox-active bipyridinium derivatives, have evolved from their initial discovery in Michaelis’ laboratory and later turned into key building blocks in supramolecular chemistry and advanced materials.
This review offers an overview of the merits and applications of materials for aqueous redox flow batteries, focusing on the design principles of redox-active materials and the development of functional materials for electrodes and membranes.
Oligo(ethylene glycol) (OEG)-substituted viologens enable superior cycling stability of the first-electron redox reaction and accessibility of the second-electron energy storage in aqueous organic redox flow batteries (AORFBs).
The unique electron-deficient viologen-based compounds are the terminally substituted 4,4′-bipyridine with excellent photoelectric response features to be applied in the preparation of stimuli-responsive materials.