This work addresses the effects of supramolecular complexation by cucurbituril (CB) on the cell potential of aqueous batteries based on ferrocene and 4,4′-bipyridinum (viologen) electroactive materials. It was previously known that the oxidation potential of cationic ferrocene derivatives is shifted to more positive values by the formation of highly stable 1 : 1 binary complexes with CB. Here, we found that the formation of 1 : 2 ternary complexes between suitably designed viologens and CB leads to a pronounced shift to more negative values in the first one-electron reduction potential of the viologen. Combining these two effects, we predict that the corresponding aqueous redox flow battery (RFB) -containing cationic ferrocene in the catholyte and viologen in the anolyte- will exhibit a potential of 1.04 V in the absence of CB and 1.30 V in the presence of suitable concentrations of CB. This substantial potential increase might be improved in future research, as the supramolecular complexation effect seems to be rather general.
- redox flow batteries
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