A bifunctional anode: DFT and AIMD Investigation of Na and K Storage on the B ₂₆ Monolayer

Using DFT with corrections for van der Waals interactions (DFT-D3), combined with ab-initio molecular dynamics (AIMD), I systematically investigate the adsorption and diffusion of Na and K atoms on the two-dimensional boron (B 26 ) monolayer for sodium/potassium-ion battery (SIB/PIB) applications. Density of states (DOS) indicates that the substrate exhibits metallic character upon adsorption, ensuring excellent electrical conductivity, which facilitates redox reactions. The binding mechanism is identified as an ionic-vdW interaction, which guarantees strong yet reversible anchoring of adatoms. The calculated diffusion energy barriers are remarkably low, at 0.39/020 eV for Na/K, indicating ultrafast ionic transport. The theoretical capacity reaches 1716 mAh g -1 for both Na and K, with average open-circuit voltages of 1.00 V and 0.82 V for SIBs and PIBs, respectively. The fully Na/K-loaded structures demonstrate robust thermal stability at 300 K via AIMD, along with excellent thermodynamic and lattice stability, with post-adsorption in-plane lattice changes confined to < 1%.