Defective SiC Nanotubes: Promising Anode Materials for Alkali Metal Ion Batteries

In this study, we explore the potential of defective one-dimensional silicon carbide nanotubes (D-SiCNTs) as high-performance anode materials in alkali metal ion batteries (AMIBs), using first-principles density functional theory calculations. The D-SiCNTs are formed by stacking bilayer SiC nanoribbons in an AA configuration, where Si(C) atoms in the top layer are aligned directly above the Si(C) atoms in the bottom layer. This stacking forms nanotubes with alternating parallel rows of Si–Si and C–C bonds on opposite sides, resulting in a unique structure that exhibits excellent mechanical, dynamic, and thermal stability. Additionally, the D-SiCNTs exhibit high electrical conductivity due to their semimetallic nature with a Dirac cone feature, which arises from the unique arrangement of Si–Si and C–C bonds. Adsorption of alkali metal ions, Li, Na, and K, on the D-SiCNTs showed that they prefer to adsorb on the C–C sites, as opposed to the Si–Si, or other sites, due to repulsion between the Si and alkali metal ions. Adsorption of the alkali metal ions on the NTs was shown to improve the electronic conductivity by inducing metallic character, suggesting their suitability for charge–discharge processes. Overall, the self-assembled D-SiCNTs display promising characteristics for applications as anode materials for AMIBs, owing to their low diffusion barrier and robust stability.