Ferrocene and Cobaltocene Derivatives for Non-Aqueous Redox Flow Batteries

Ferrocene and cobaltocene and their derivatives are studied as new redox materials for redox flow cells. Their high reaction rates and moderate solubility are attractive properties for their use as active materials. The cyclability experiments are carried out in a static cell; the results showed that these materials exhibit stable capacity retention and predictable discharge potentials, which agree with the potential values from the cyclic voltammograms. The diffusion coefficients of these materials are 2 to 7 times higher than those of other non‐aqueous materials such as vanadium acetylacetonate, iron tris(2,2′‐bipyridine) complexes, and an organic benzene derivative. Back on the metallo‐scene! Metallocenes are investigated as new redox materials in non‐aqueous redox flow batteries. Several pairs of ferrocene and cobaltocene derivatives are studied. Modification with functional groups and integration of transition‐metal ions can change the electrochemical properties of the redox materials, improving current density and discharge potential.