A DFT-D guided surface engineering of 2-D functionalized graphyne analogue covalent triazine frameworks as a high-capacity anode material of Mg-ion battery

Abstract

In the present study, we have explored the potential application of pure and functionalized 2-D graphyne-like covalent triazine framework (GYCTF) as an anode material for Mg-ion batteries, using dispersion-corrected DFT. The accurate interaction energies are crucial for energy storage and battery applications as they are directly related to the key properties in electrochemistry, such as storage capacities, in general, and open-circuit voltages (OCVs), in particular. We have found that Mg preferably adsorbs above the center of all carbon six-membered rings of GYCTF with adsorption energy of about 83.4 kcal mol−1. After functionalization, -SH increases the maximum coverage of Mg on surface from 4 to 9 Mg. Also, –CH3 strongly reduces the specific capacity of GYCTF in MIB application. After functionalization, -SH increases the maximum coverage of Mg on the surface from 4 to 9 Mg. Also, –CH3 strongly reduces the specific capacity of GYCTF in MIB application. The single-layer GYCTF-SH can be magnesiated on both sides yielding Mg9C13N3S4H4 with a storage capacity as high as 1462.4 mAh g−1 with an average OCV of 0.68 V. Our findings show better results in terms of storage capacity, negligible volume expansion, low OCV, and low diffusion energies comparing with commonly studied 2-D materials, making thiol-functionalized GYCTF a promising candidate as an anode material for Mg- ion batteries.