Continuously Alternating Storage of Anion and Cation Toward a High-Performance Bipolar Conjugated Polymer Cathode

Rapid and sequential ion insertion is impeded in the single host organic electrodes, primarily due to Coulomb repulsion between ions with identical charges, which creates an irreconcilable conflict between capacity and rate performance. Herein, a bipolar conjugated donor-acceptor (D-A) polymer (PTZ-Pz) is designed and synthesized with the co-storage of opposite ions by utilizing the electron-donating phenothiazine (PTZ) unit and the electron-withdrawing phenazine (Pz) unit as the building blocks. It demonstrates that the continuously alternate storage of anions and cations can facilitate the charge transfer processes and thereby accelerate the reaction dynamic of the PTZ-Pz cathode. Consequently, the D-A polymer PTZ-Pz shows a high specific capacity of 208 mAh g^-1. The electrode exhibits an ultra-long cyclability of more than 80 000 cycles, with an excellent rate performance of 116 mAh g^-1 at 20 A g^-1. Benefiting from the fast kinetics, the PTZ-Pz cathode can operate well at a high mass loading of 44.2 mg cm^-2. The enhanced energy and power density via alternate storage anions and cations mode may facilitate the exploration of new electrode materials for aluminum batteries.