Ladder-type conjugated poly(benzobisimidazobenzophenanthroline) cathode for aluminum-ion batteries

Rechargeable aluminum-ion batteries have gained substantial attention for large-scale energy storage owing to aluminum's high volumetric capacity (8035 mAh cm^-3), abundance (8.23%), low cost, and safety. However, the primary challenge in the development of such batteries lies in the identification of suitable cathode materials for intercalating aluminum-complex ions. In this study, we introduce a novel strategy for fabricating a ladder-type conjugated poly(benzobisimidazobenzophenanthroline) (BBL) cathode material. This material effectively harnesses CO and CN groups as active sites for redox reactions, thereby facilitating the efficient intercalation and deintercalation of aluminum-complex ions. The BBL cathode demonstrated outstanding electrochemical performance with a reversible capacity of 100 mAh g^-1 at a current density of 200 mA g^-1 and excellent cyclability, which exceeded over 1000 cycles. Additionally, the BBL cathode features a stable discharge plateau in the voltage range of 1.1-1.5 V, which is attributed to the spontaneous and uniform adsorption of Al-complex ions at the CO and CN active moieties.