The Metallocene Battery ‐ Ultrafast Electron Transfer Self Exchange Rate Accompanied by a Harmonic Height Breathing

The first all-metallocene rechargeable battery consisting of poly-cobaltocenium/- and poly-ferrocene/reduced graphene oxide composites as anode and cathode was prepared. The intrinsically fast ET self-exchange rate of metallocenes was successfully combined with an efficient ion-percolation achieved by molecular self-assembly. The resulting battery materials show ideal Nernstian behavior, is thickness scalable up to > 1.2 C cm -2 , and exhibit high coulombic efficiency at ultrafast rates (200 A g -1 ). Using aqueous LiClO 4 , the charge is carried exclusively by the anion. The ClO 4 - intercalation is accompanied by a reciprocal height change of the active layers. Principally, volume changes in organic battery materials during charging/discharging are not desirable and represent a major safety issue. However, here, the individual height changes - due to ion breathing - are reciprocal and thus prohibiting any internal pressure build-up in the closed-cell, leading to excellent cycling stability.