Carbonyl-Rich Polyimide Covalent Organic Frameworks as Anode Coating for Uniform Sodium Deposition

Two-dimensional covalent organic frameworks (2D COFs), by virtue of their structural diversity, high specific surface area, and facile functionalization, have emerged as a promising anode coating for sodium metal batteries (SMBs). Herein, we report two polyimide COFs (TATT-NTCDA‑COF and TATT-PMDA‑COF) constructed from isocyanurate-based amine building blocks, which feature profuse ion-binding active sites and a robust, ordered framework, thereby significantly enhancing ion transport, fostering uniform sodium deposition, and suppressing dendrite growth. Benefiting from this unique design and its reliable stability, the symmetric cell based on TATT-NTCDA‑COF operates stably for over 1200 h at 0.1 mA cm^-2. When assembled into a full cell with a commercial Na₃V₂(PO₄)₃ (NVP) cathode, it delivers an initial discharge capacity of 107.4 mAh g^-1, retains 9.3% capacity after 800 cycles at 1 C, and maintains over 90% capacity retention even after 1390 cycles at 5 C and 750 cycles at 10 C. Thus, the rational design of carbonyl-rich 2D COFs is of great significance for the construction of artificial anode coatings for SMBs.