Electropolymerized Bipolar Poly(2,3-diaminophenazine) Cathode for High-Performance Aqueous Al-Ion Batteries with An...

Achieving reversible insertion/extraction in most cathodes for aqueous aluminum ion batteries (AAIBs) is a significant challenge due to the high charge density of Al³⁺ and strong electrostatic interactions. Organic materials facilitate the hosting of multivalent carriers and rapid ions diffusion through the rearrangement of chemical bonds. Here, a bipolar conjugated poly(2,3-diaminophenazine) (PDAP) on carbon substrates prepared via a straightforward electropolymerization method is introduced as cathode for AAIBs. The integration of n-type and p-type active units endow PDAP with an increased number of sites for ions interaction. The long-range conjugated skeleton enhances electron delocalization and collaborates with carbon to ensure high conductivity. Moreover, the strong intermolecular interactions including π-π interaction and hydrogen bonding significantly enhance its stability. Consequently, the Al//PDAP battery exhibits a large capacity of 338 mAh g^-1 with long lifespan and high-rate capability. It consistently demonstrates exceptional electrochemical performances even under extreme conditions with capacities of 155 and 348 mAh g^-1 at -20 and 45 °C, respectively. In/ex situ spectroscopy comprehensively elucidates its cation/anion (Al³⁺/H₃O⁺ and ClO₄ ^-) storage with 3-electron transfer in dual electroactive centers (C═N and -NH-). This study presents a promising strategy for constructing high-performance organic cathode for AAIBs over a wide temperature range.