Revealing the anodic performance of Janus Mxenes (ABN, A = Sc; B = Zr, Nb, Mo) for magnesium-ion batteries: a first-principles study

Abstract

Rechargeable magnesium-ion batteries (MIBs) have attracted attention as alternatives to lithium-ion batteries for next-generation energy storage systems due to their low cost and the abundance of magnesium. However, the absence of suitable electrode components for long-term use has prevented the exploration of MIBs. In this work, three computationally predicted Janus MXenes, namely ScZrN, ScNbN, and ScMoN, are investigated as anode materials using density functional theory (DFT). Various parameters, including adsorption energy, charge density difference (CDD), band structure, density of states (DOS), and charge transfer, were analyzed. All the nanosheets exhibit metallic behavior, confirmed by the band structures from HSE06 hybrid functional calculations. These MXenes demonstrate good structural stability, evidenced by negative cohesive energy and Gibbs free energy values. In the adsorption energy calculations, Mg atoms are adsorbed on the three nanosheets with favorable adsorption energies of −1.66 eV to −2.44 eV. Low diffusion barriers of 0.49, 0.26, and 0.37 eV are observed for the ScZrN, ScNbN, and ScMoN, respectively. Moderately high specific capacities of 555.2, 666.4, and 384.5 mAh g⁻¹ are calculated for ScNbN, ScZrN, and ScMoN, respectively. Therefore, these materials can be considered as potential anode candidates for MIBs, although they require further experimental validation.