Novel Janus-MNbCO2 (M = Mo, Ta) for high-performance Li-Ion batteries: Insights from first-principles calculations

Gonzalo F.M.; Ordonez-Miranda J.; Rivera V.J.R.; Garcia J.A.C.; Sambrano J.R.; Dias A.C.; Moreira M.L.; Piotrowski M.J.; Flores E.M. · Surfaces and Interfaces (2026) · DOI: 10.1016/j.surfin.2025.108295

Resumen

Two-dimensional Janus MXenes offer a built-in vertical polarity that can be harnessed to program interfacial energetics for electrochemical energy storage. Here, we predict and rationalize the structure–stability–transport relationships of two O-terminated double transition-metal Janus carbides, MoNbCO2 and TaNbCO2. DFT, AIMD, and phonon dispersion confirm robust thermal and dynamical stability; both monolayers are metallic with transition-metal d states dominating near EF. Cohesive energies of −9.17 (MoNbCO2) and −9.46 eV/atom (TaNbCO2) indicate strong bonding, while elastic constants yield nearly isotropic in-plane responses (E=251/284 N/m and G=95/111 N/m for Mo/Ta systems). The Janus polarity drives termination-specific Li–surface interactions: Li binds most strongly at C-aligned hollows on both faces, with adsorption energies down to ∼−4.5eV (Mo–O side), and undergoes fast, bridge-assisted diffusion with representative barriers ∼0.26eV on TaNbCO2. Stepwise lithiation up to Li6MNbCO2 provides high theoretical capacities of ∼691 mAh/g (Mo) and ∼506 mAh/g (Ta), with moderate OCVavg of 1.11 V (Mo) and 0.92 V (Ta) across the reversible lithiation window—indicating low risk of Li plating and favorable compatibility with solid-electrolyte operation. Crucially, a polarity-mediated functional divergence emerges: MoNbCO2 favors energy-dense storage via stronger Li binding and higher capacity, whereas TaNbCO2 offers superior ion-transport kinetics with lower migration barriers and enhanced rate capability. These results establish selective transition-metal pairing in Janus MXenes as a tunable design principle to target either high-energy or high-power all-solid-state Li-ion battery applications. Copyright

Instituciones: Universidad Nacional Jorge Basadre Grohmann