Janus transition-metal carbo-chalcogenide Nb2CSSe anode enabling efficient Li storage

Rivera V.J.R.; Gonzalo F.M.; Laura G.A.; Simões A.Z.; Delgado E.R.; Mendoza H.E.N.; Sambrano J.R.; Piotrowski M.J.; Flores E.M. · Journal of Energy Storage (2026) · DOI: 10.1016/j.est.2026.120380

Resumen

Li-ion batteries (LIBs) require anodes that unite metallic conduction, fast Li+ transport, benign interfacial chemistry, and mechanical resilience. Using density-functional theory (DFT) with climbing-image nudged elastic band (CI-NEB), ab initio molecular dynamics (AIMD), and a machine-learned phonon workflow, we identify the Janus transition-metal carbo-chalcogenide Nb2CSSe as a promising anode material for LIBs. The Nb2C scaffold remains metallic with Nb d states at EF, while the S/Se asymmetry introduces a built-in polarity that strengthens adsorption on the S face and drives nearly complete Li ionization (∼0.86|e|). Single-atom binding is exothermic at Nb- and C-top hollows with a small site splitting, enabling facile lateral rearrangement. Minimum-energy paths on both faces show low migration barriers (∼0.24–0.26 eV) and Arrhenius diffusivities near 10−6 cm2 s−1 at 300 K, consistent with high-rate operation. A face-alternating adlayer sequence (nine Li per layer) yields a theoretical capacity of 458.81 mAh g−1 and an average open-circuit voltage of ∼0.91 V, balancing dendrite suppression with large full-cell voltage. The monolayer is mechanically stiff with weak in-plane anisotropy, exhibits no imaginary phonons, and sustains stable, non-clustering adlayers in 300 K AIMD up to full coverage. These results highlight how a metallic carbide core combined with polarity-tuned chalcogen terminations delivers fast, face-selective Li+ transport and robust interfacial behavior, offering a transferable design strategy for Janus carbo-chalcogenides in LIBs.

Instituciones: Universidad Nacional Jorge Basadre Grohmann