A Microporous Covalent–Organic Framework with Abundant Accessible Carbonyl Groups for Lithium‐Ion Batteries

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A key challenge faced by organic electrodes is how to promote the redox reactions of functional groups to achieve high specific capacity and rate performance. Here, we report a two‐dimensional (2D) microporous covalent–organic framework (COF), poly(imide‐benzoquinone), via in situ polymerization on graphene (PIBN‐G) to function as a cathode material for lithium‐ion batteries (LIBs). Such a structure favors charge transfer from graphene to PIBN and full access of both electrons and Li + ions to the abundant redox‐active carbonyl groups, which are essential for battery reactions. This enables large reversible specific capacities of 271.0 and 193.1 mAh g −1 at 0.1 and 10 C, respectively, and retention of more than 86 % after 300 cycles. The discharging/charging process successively involves 8 Li + and 2 Li + in the carbonyl groups of the respective imide and quinone groups. The structural merits of PIBN‐G will trigger more investigations into the designable and versatile COFs for electrochemistry.