A DFT study of monolayer magnesium carbide (MgC2) as a potential anode for (Li, Na, K) alkali metal-ion batteries

Abstract

Magnesium carbide (MgC₂) is the latest two-dimensional monolayer material with semiconductor properties containing 0.25 eV band gap. Upon adsorption of the Li/Na/K the semiconducting behavior of material changes to metallic. These properties make it a good choice for electrical usage. We employed first-principles evaluations in this study to see whether MgC₂ could work as an anode of chargeable alkali-metal-ion batteries. Our findings show that lithium, sodium, and potassium adsorbed on MgC₂ offer higher electrical efficiency, with −0.92, −1.54, and −2.11 eV adsorption energies, respectively. Its structure remained intact upon the lithiation, sodiation, and potassiation processes. It demonstrated elevated storage ability for Li, Na, and K ions, delivering 6100, 5545, and 4436 mA h g⁻¹, respectively. The diffusion energy barriers for Li, Na, and K ions are 0.9 eV, 0.13 eV, and 0.28 eV, respectively. Furthermore, for Alkali (Li/Na/K) ions, MgC₂ offered open circuit voltages (OCV) of 0.23, 0.53, and 0.85 V, respectively. The exceptional performance of MgC₂ makes it a prominent candidate as an anode material for alkali metal (Li/Na/K) ion batteries.