N and B co-doping to enhance Li adsorption and diffusion properties on silicene/graphene heterostructures: Insights from density functional theory

Abstract

Due to the structural properties of silicene itself, a substrate material is required to support it in practical use. Graphene is considered to be a good substrate material because of its many excellent properties. However, the heterostructure (Si/G) composed of graphene and silicene is low in stability, and it needs to be improved to enhance its stability. In this work, N and B co-doped graphene and silicene heterostructures (SiB/GN) are constructed with the aim of improving structural stability and obtaining better properties. Calculations show that the SiB/GN heterostructure still belongs to the vdW heterostructure. B doping can disrupt the topologically protected surface quantum states of graphene and silicene, and N doping can further increase the Coulombic attraction between graphene and silicene, thus increasing the binding energy to 22.58 meV Å⁻¹, nearly twice that of Si/G. The density of states results show that the SiB/GN heterostructure is metallic before and after lithium embedding, which ensures good electrical conductivity. Due to the synergistic effect SiB/GN heterostructure exhibits stronger Li adsorption performance (2.36 eV), and lower diffusion barrier (0.229 eV), which is conducive to the inhibition of lithium dendrite formation and the improvement of the battery multiplicity charge/discharge performance.