β‐Ketoenamine‐Linked Covalent Organic Framework with Co Intercalation: Improved Lithium‐Storage Properties and Mechanism for High‐Performance Lithium‐Organic Batteries

Abstract As a new kind of crystalline porous polymers, covalent organic frameworks (COFs) exhibit great potential as electrode materials for rechargeable metal‐ion batteries due to their stable and adjustable structure, high porosity and abundant electrochemical active centers. In this paper, facile one‐step synthesis process is proposed to obtain the cobalt ion intercalated two‐dimensional β‐ketoenamine‐linked COF (Co−DAAQ−TFP‐COF, denoted as Co‐COF). The intercalation of Co ion in adjacent two layered structure of COF via coordination effects can activate the Li+ storage ability of aromatic ring in the original COF, greatly improve the utilization of redox active sites, shorten the migration length of electrons and ions, and promote fast lithium reaction kinetics. Adopted as the anode for lithium‐ion batteries, substantial improvement on the reversible capacity and cycling performance can be achieved for the obtained Co intercalated COF electrode (780 mAh g−1 after 200 cycles at 100 mA g−1) compared to original COF electrode (120 mAh g−1 under the same condition). The two‐dimensional COF materials with morphology justification and/or performance improvement via metal ion intercalation would promote the application of COF related electrodes for other energy‐storage fields.