Electropolymerized Bipolar Poly(2,3-diaminophenazine) Cathode for High-Performance Aqueous Al-Ion Batteries with An Extended Temperature Range of-20 to 45 C

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 pi-pi 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 degrees C, respectively. In/ex situ spectroscopy comprehensively elucidates its cation/anion (Al3+/H3O+ and ClO4-) storage with 3-electron transfer in dual electroactive centers (CN and -NH-). This study presents a promising strategy for constructing high-performance organic cathode for AAIBs over a wide temperature range. The high charge density and strong electrostatic interactions of Al3+ present a significant challenge in achieving high-performance aqueous aluminum-ion batteries. Here, a bipolar polymer with a long-range conjugated skeleton, high electronic/ionic conductivity, and a three-electron reaction mechanism is designed that enables high-rate and long-term cycling performance, even within a wide temperature range (-20-45 degrees C). image