NbTaCSe2 Janus carbo-chalcogenide as a high-performance anode for lithium-ion batteries

Rivera V.J.R.; Mamani-Gonzalo F.; Mosqueira-Yauri J.; Mamani N.F.C.; Ayala-Arenas J.; Simoes A.Z.; Tian F.; Sambrano J.R.; Piotrowski M.J.; Mamani Flores E. · Applied Surface Science (2026) · DOI: 10.1016/j.apsusc.2026.167694

Resumen

Two-dimensional Janus materials have recently emerged as promising candidates for electrochemical energy storage due to their intrinsic structural asymmetry and tunable surface chemistry. In this work, the Li-storage capability of the Janus transition-metal carbo-chalcogenide NbTaCSe2 monolayer is systematically investigated using density-functional theory (DFT), climbing-image nudged elastic band (CI-NEB) calculations, and ab initio molecular dynamics (AIMD) simulations. Electronic structure calculations reveal that the NbTaCSe2 framework retains metallic character, with transition-metal d orbitals crossing the Fermi level and enabling efficient electronic conduction during lithiation. The Nb- and Ta-terminated surfaces provide nonequivalent adsorption environments for Li atoms, yet both sides exhibit strong Li binding accompanied by a charge transfer of about 0.86|e|, indicating largely ionic interactions with the carbide lattice. Hollow adsorption sites are energetically preferred, while the small energy differences among nearby configurations suggest that Li atoms can readily redistribute across the surface. Li diffusion along the most favorable pathways shows low migration barriers of approximately 0.26–0.28eV, corresponding to diffusivities on the order of 10−6 cm2 s−1 at 300 K, indicative of rapid in-plane Li transport. Progressive lithiation modeled by sequential Li adlayer deposition on alternating surfaces up to ten Li layers results in a maximum theoretical capacity of 604 mAh g−1 and an average open-circuit voltage of 0.53 V. In addition, the NbTaCSe2 monolayer exhibits high in-plane stiffness with weak elastic anisotropy and phonon spectra free of imaginary frequencies, confirming dynamical stability. AIMD simulations at 300 K further demonstrate that Li adlayers remain well dispersed without clustering even at full lithiation. These results indicate that the combination of a conductive carbide backbone and Janus surface asymmetry promotes strong Li adsorption, fast diffusion, and structural stability, suggesting NbTaCSe2 as a promising anode material for high-rate lithium-ion batteries.

Instituciones: Universidad Nacional de San Agustín de Arequipa; Universidad Nacional Jorge Basadre Grohmann