Exploring covalent organic frameworks as high-capacity and long-cycling anode materials for lithium-ion batteries.

It is essential to advance the development of lithium-ion batteries (LIBs) characterized by high specific capacity and extended cycle life. Covalent organic frameworks (COFs) have emerged as pivotal materials in achieving this objective due to their long-range ordered porous structures and ease of modification. In this work, we designed and synthesized two types of β-ketoenamine-linked COFs, namely TP-3J-COF and TP-3Q-COF, which incorporate multiple redox sites. These COFs were subsequently applied to the anode of LIBs, resulting in the successful fabrication of batteries that demonstrate both high specific capacity and prolonged cycle life. Furthermore, we prepared two composites by in situ growth of COFs on carbon nanotubes (CNTs). The synergistic interaction between the COFs and CNTs enabled the TP-3J-COF@CNT and TP-3Q-COF@CNT composites to achieve maximum specific capacities of 1020 mAh g^-1 and 731 mAh g^-1, respectively, along with cycle lives exceeding 1400 and 3000 cycles. This research underscores the efficacy of the strategy involving the construction of COFs with multiple redox-active units and their composite formation with CNTs as a robust approach for the development of high-performance LIBs.