High‐Redox‐Potential p‐Type Covalent Organic Frameworks With Abundant Active Sites for High‐Voltage and Long‐Life Lithium‐Ion Battery Cathodes

ABSTRACT Covalent organic frameworks (COFs) hold great promise for advancing lithium‐ion battery (LIB) cathode performance and overcoming resource bottlenecks due to their abundant elemental synthesis, tunable functionality, and stability. However, most COF cathodes commonly suffer from relatively low redox potential and/or poor charge‐storage capability, which limits their energy densities. Here, we report the rational design of a p‐type high‐redox‐potential COF by polymerizing 10,15‐dihydro‐5,10,15‐triethyl‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazole‐3,8,13‐triamine (TAT‐NH 2 ) and 9‐methyl‐9H‐carbazole‐3,6–dicarboxaldehyde (Cz‐CHO) building blocks (namely, TAT‐Cz COF). The COF features an extended π‐conjugated framework and a moderate pore size (∼2.3 nm), enabling efficient anion transport and insertion/de‐insertions. More importantly, by engineering high‐redox‐potential nitrogen sites into the COF, a high operating working voltage (3.0–4.5 V vs. Li + /Li) is achieved. As an LIB cathode, it delivers a high reversible capacity of 131 mAh g −1 at 0.1 C, along with excellent rate performance (65 mAh g −1 at 20 C). Additionally, it demonstrates exceptional cycling stability, retaining 76 mAh g −1 after 3000 cycles at 1.0 C with only 0.0114% capacity decay per cycle. In situ spectra and theoretical calculations reveal a highly reversible charge‐storage mechanism involving N + radical cations coordinated with PF 6 − anions. This work provides insights for developing high‐redox‐potential COFs with tailored structures and enhanced performance for high‐energy‐density organic cathodes.