Imidazole-linked covalent organic polymers with abundant oxygen and nitrogen active centers for advanced aqueous zinc-organic batteries

Organic polymer cathodes are of long-standing interest for aqueous zinc-ion batteries (AZIBs) due to their specific redox-sites and stable structural frameworks. However, the high redox potential of Zn anode and poor electrical conductivity as well as sluggish mass/charge transfer of organic polymers prevent most of organic cathodes from effectively participating in the redox reaction. Therefore, designing and applying suitable cathodes through molecular engineering for high-performances AZIBs still remains a challenging task. Herein, we design an imidazole-linked polymer PMTP used as cathode for AZIBs by the condensation of benzene-1,3,5-tricarbaldehyde (BT) linker and 2,3,7,8-Tetraaminophenazine-1,4,6,9-tetraone (TAPT) redox-ligand, which exhibits six-electrons reaction process of each structural unit. In addition, the PMTP@CNT-X composite (X denotes the mass percent of CNTs in composite) is fabricated by in-situ polymerization of PMTP on the surface of carbon nanotubes (CNTs) to promote the charge/mass transfer. Benefiting from the integration strategy, PMTP@CNT-40 delivers high redox-active site utilization, thus achieving high capability of 230 mA h g−1 and long lifespan up to 4000 cycles at 3 A/g. This work may shed light on designing and developing novel organic cathodes for advanced AZIBs.