When are Two-Dimensional Covalent Organic Frameworks Good Electrodes for Lithium Ion Batteries? A Data-Driven Analysis

Two-dimensional covalent organic frameworks (2D COFs) are emerging as sustainable organic electrode candidates for lithium-ion batteries. Despite more than a decade of research, existing heuristics for designing electroactive COFs lack generality, and the suitability of these materials as alternatives to conventional electrodes remains poorly resolved. Here, we map structure-electrode-function relationships across 1099 experimentally synthesized 2D COFs from the CoRE COF database by developing a data-driven framework integrating density-functional theory computations with machine learning models and establishing atomic-level design rules governing electrode behavior. We uncover that cathode-like character originates from dense, multidentate nitrogen and oxygen rich coordination pockets at pore walls, characteristic of imide, acylhydrazones, keto-amine linkages, and π-macrocycles, whereas anode-like behavior is encoded by spatially separated redox sites and π-rich interlayer galleries that sustain weak, reversible Li⁺ intercalation. Sequential voltage, capacity, and conductivity-based screening across the database yields 14 anode and 14 cathode candidates. We show that the known chemical space of 2D COFs cannot outperform inorganic electrodes in terms of operating voltages. However, strategic pairing of 2D anode|cathode pairs within an all-organic lithium battery architecture delivers full-cell voltages exceeding 2 V with capacities above 200 mAh g^-1 on both electrodes, surpassing small organic molecules and polymer counterparts.