Lithium storage mechanisms in oxygen-functionalized Nb–Ta double transition metal MXenes controlled by metal ordering

Gonzalo F.M.; Rivera V.J.R.; Sambrano J.R.; Ordonez-Miranda J.; Simoes A.Z.; Laura G.A.; W․ R.C.; Moreira M.L.; Piotrowski M.J.; Flores E.M. · Journal of Colloid and Interface Science (2026) · DOI: 10.1016/j.jcis.2026.141185

Resumen

The effects of surface functionalization and metal ordering on the structural, mechanical, and electrochemical properties of two-dimensional transition metal carbide MXenes remain insufficiently understood, particularly for double-metal systems. Nb2TaC2 and Ta2NbC2 monolayers, in bare and oxygen-functionalized forms, are studied using density functional theory to determine how these factors affect lithium adsorption, diffusion, and storage performance. Oxygen functionalization increases in-plane stiffness (Young's modulus up to 384.7 N/m) and stabilizes Poisson's ratios, while lithium preferentially adsorbs at metallic sites on bare MXenes and at carbon sites on O-functionalized surfaces, with adsorption energies reaching −3.70 eV. Nudged elastic band calculations show that oxygen functionalization slightly increases diffusion barriers, from 0.05 to 0.21 eV for Nb2TaC2 and from 0.06 to 0.24 eV for Ta2NbC2, while fast Li-ion mobility is maintained. Open-circuit voltage analysis indicates average voltages of 0.74 to 0.95 V with capacities up to 412 mAh/g. These results provide design guidelines for tuning surface chemistry and metal ordering in double-metal MXene anodes for Li-ion batteries.

Instituciones: Universidad Nacional Jorge Basadre Grohmann