Tuning the electronic and electrochemical properties of 2D SiC by defect insertion for next-generation metal-ion battery anodes: first principles prediction

Abstract

We employ density functional theory (DFT) to investigate how Stone-Wales (SW) defects modulate the electronic and electrochemical properties of two-dimensional silicon carbide (SiC) monolayer for sodium (Na)-, potassium (K)-, and magnesium (Mg)-ion batteries. The SW-SiC structure is energetically feasible and dynamically stable, with defect formation reducing the bandgap by ~ 70% and enhancing electronic conductivity. Compared to pristine SiC, SW-SiC exhibits stronger adsorption for Na (- 0.89 eV) and K (- 1.52 eV) with pronounced charge transfer at the adatom-substrate interface. Theoretical capacities of 300 and 600 mAh g⁻¹ for Na and K, respectively, are achieved, along with low diffusion barriers (0.88 eV for Na, 0.54 eV for K) and favorable open-circuit voltages (0.44 V, 0.70 V). Minimal structural distortion upon ion insertion confirms structural stability. These results elucidate the defect-property interplay in 2D SiC and establish SW defect engineering as a viable approach for optimizing condensed-phase anode materials beyond lithium systems.