Reducing the shuttle effect in Li-S batteries with oxygenated penta-SiC₂ monolayer

Oxygen functionalized penta-SiC₂ (p-SiC₂/O) combines a robust all pentagon 2D framework with polar epoxide anchors that afford both strong Li-polysulfide binding and enhanced electronic conductivity. This study explores the optimization and functionalization of two-dimensional penta-SiC₂ for lithium-sulfur (Li-S) batteries. The structure optimization was confirmed through formation energy calculations. Functionalizing penta-SiC₂ with oxygen (epoxy groups) significantly enhanced adsorption properties for sulfur (S₈) and lithium polysulfides (Li₂S_n), with a binding energy of −4.39 eV, mitigating the shuttle effect. Oxygen functionalization reduced the band gap from 1.60 to 1.52 eV, improving electronic conductivity, as confirmed by density of states (DOS) analysis. Gibbs free energy profiles showed strong binding interactions for sulfur reduction reactions, with a ΔG of −1.52 eV for Li₂S adsorption (−1.52 eV) promoting immobilization of discharge products and enhancing cycling stability. This work highlights p-SiC₂/O as a promising electrode material, offering insights into its structural and electronic properties for advancing Li-S battery performance.