A DFT modeling of 4-cyclohexene-1,3-dione embedded in covalent triazine framework as a stable anode material for Li-ion batteries

Abstract

Developing porous organic anode materials with outstanding electrical conductivity and high capacity is crucial to enhancing the performance of Li-ion batteries (LIBs). Herein, 4-cyclohexene-1,3-dione-functionalized covalent triazine framework (CYC-CTF0) monolayer as a new anode material in LIBs was explored through density functional theory calculations. The monolayer demonstrates good thermal, mechanical, and cycling stability and has a strong affinity for Li-ions to bind to the C=O and C=N redox-active sites. The adsorption of Li-ions transforms the CYC-CTF0 monolayer from being semiconducting to becoming metallic, reflecting its high electrical conductivity. Remarkably, the lattice undergoes a minimal expansion of 1.1 % throughout the charging and discharging process, suggesting an extended cycle life. The unit cell of the monolayer can be fully loaded with four Li-ions at different adsorption sites, exhibiting a specific theoretical capacity of 585.41 mAh g−1 and a low open-circuit voltage of 0.12 V. Moreover, the adsorbed Li-ions display a low diffusion energy barrier of 0.17 eV, enabling effective rates of charging and discharging. Our findings reveal the unique characteristics of the CYC-CTF0 monolayer as a promising anode material in LIBs.