Sc₂C as a Promising Anode Material with High Mobility and Capacity: A First‐Principles Study

Abstract

Two-dimensional (2D) Sc₂ C, an example of a MXene, has been attracting extensive attention due to its distinctive properties and great potential in applications such as energy storage. In light of its high capacity and fast charging-discharging performance, Sc₂ C exhibits significant potential as an anode material for lithium- and sodium-ion batteries. Herein, a systematic investigation of Li/Na atom adsorption and diffusion on Sc₂ C planes was performed based on density functional calculations. The metallic character of pristine and adsorbed Sc₂ C ensures desirable electric conductivity, which indicates the advantages of 2D Sc₂ C for lithium- and sodium-ion batteries. A significant charge transfer from the Li/Na atoms to Sc₂ C is predicted, which indicates the cationic state of the adatoms. In addition, the diffusion barriers are as low as 0.018 and 0.012 eV for Li and Na, respectively, which illustrates the high mobility and cycling ability of Sc₂ C. In particular, each formula unit of Sc₂ C can adsorb up to two Li/Na atoms, which corresponds to a relatively high theoretical capacity of 462 or 362 mAh g^-1 . The average electrode potential was calculated to be as low as 0.32 and 0.24 V for stoichiometric Li₂ Sc₂ C and Na₂ Sc₂ C, respectively, which makes Sc₂ C attractive for the overall voltage of the cell. Herein, our results suggest that Sc₂ C could be a promising anode candidate for both lithium-ion and sodium-ion batteries.