Electropolymerized organic N/P bipolar cathode toward high energy and high power density sodium dual-ion batteries†

Sodium dual ion batteries (SDIBs) have received considerable attention recently for large-scale energy storage systems due to their low cost and inherent safety. Nevertheless, SDIBs remain a subject of investigation as efficient cathode materials for high energy densities and are still under development. Bipolar organic compounds stand out for their ability to combine both the merits of high voltage of p-type and high capacity of n-type electrode materials. Herein, we developed a bipolar organic cathode bearing n-type anthraquinone (AQ) and p-type triphenylamine (TPA) through in situ electropolymerization for efficient sodium dual-ion storage. The combined high capacity of n-type and high voltage of p-type materials serve to achieve exceptional electrochemical performances of SDIBs in terms of high energy density and high power density. Experimental and theoretical calculations validate the bipolar energy storage mechanism. This work broadens the chemical scope of bipolar organic cathode materials for state-of-the-art SDIBs.