Triazine- and Keto-Functionalized Porous Covalent Organic Framework as a Promising Anode Material for Na-Ion Batteries: A First-Principles Study

Because of the low cost and plentiful resources of sodium as compared to lithium, sodium-ion batteries (SIBs) are becoming promising alternatives to lithium-ion batteries for large-scale electrochemical energy storage applications. However, the non-availability of appropriate anode materials restricts the use of SIBs. We have herein made an attempt to investigate the suitability of a triformylphloroglucinol (TP) and triazine triamine (TT)-based bilayer organic framework (TPTT) as an anode material for SIBs using density functional theory-based computations. Our study reveals that the bilayer TPTT is a direct band gap semiconductor with a band gap value of 2.64 eV. The triazine framework undergoes a transition from semiconductor to metal after adsorption of sodium at the most favorable carbonyl oxygen (CO) site, thus ensuring good electrical conductivity. The good electrical conductivity, moderate diffusion barrier (0.56 eV), high theoretical specific capacity (855 mA h/g), average voltage (0.43 V) in the range required for suitable anode materials (0.1–1.00 V), and structural flexibility compel us to infer that the bilayer TPTT may be a potential candidate as an anode material for SIBs.