First-Principles Calculations for S-Doped Mo2C Monolayer As Anode for Magnesium-Ion Batteries

First-principles calculations were performed to investigate the potential of S-doped Mo2C monolayer as an anode material for magnesium-ion batteries. Our results show that the adsorption energies of Mg on the H1, TC1, TMo1, and B4 sites of S-doped Mo2C are –1.647, –1.565, –1.501, and –1.516 eV, respectively, which are 14.5, 9.4, 6.8, and 7.7% lower than those on the pristine Mo2C monolayer. These findings indicate that S incorporation enhances Mg adsorption. Mg diffusion between two adjacent favorable sites via a symmetric site on S-doped Mo2C exhibits fast diffusion. Density-of-states calculations reveal metallic behavior and favorable electronic conductivity for S-doped Mo2C. Moreover, the S-doped Mo2C monolayer delivers a high theoretical capacity of 1040.02 mA h g–1. The open-circuit voltage ranges from 0.32 to 0.87 V, with an average value of 0.51 V. Consequently, S-doped Mo2C is a promising anode candidate for magnesium-ion batteries.