Polyimide‐Linked Hexaazatriphenylene‐Based Porous Organic Polymer with Multiple Redox‐Active Sites as a High‐Capacity Organic Cathode for Lithium‐Ion Batteries

Abstract

AbstractThe development of high‐capacity, sustainable cathode materials remains a critical challenge in advancing lithium‐ion battery technologies for next‐generation energy storage. Organic electrode materials (OEMs) represent a promising alternative to conventional inorganic cathodes, owing to their composition from earth‐abundant elements and chemically tunable structures that enable high theoretical capacities. Herein, a polyimide‐linked porous organic polymer (HAT‐PTO) is reported to be synthesized via a straightforward hydrothermal reaction from redox‐active hexaazatriphenylene (HAT) and pyrene‐4,5,9,10‐tetraone (PTO) building blocks. The resulting HAT‐PTO framework incorporates multiple redox‐active C═O and C═N centers, delivering a high theoretical capacity of 484 mAh g−1. To overcome limitations in electronic conductivity, hybrid materials are synthesized by in situ growth of HAT‐PTO on multiwalled pristine (CNT) and carboxyl‐functionalized carbon nanotubes (cCNT). Notably, the HAT‐PTO‐cCNT hybrid delivers a high capacity of 397 mAh g−1 at C/10, outstanding rate capability of 225 mAh g−1 at 20 C, and long‐term cycling stability, retaining 171 mAh g−1 after 6000 cycles at 2 C. Ex situ FT‐IR, supported by density functional theory (DFT) calculations, confirms the involvement of both HAT and PTO units in the charge storage mechanism. This work presents a molecular design strategy and scalable synthesis approach toward high‐performance organic cathodes, paving the way for durable, high‐rate lithium‐organic batteries.